Walen v. United States of America

UNITED STATES DISTRICT COURT
FOR THE DISTRICT OF COLUMBIA

MARY LOU WALEN,

Plaintiff,
Civil Action No. 15-1718 (BAH)
v.
Chief Judge Beryl A. Howell
UNITED STATES OF AMERICA, et al.,

Defendants.

MEMORANDUM OPINION

The plaintiff, Mary Lou Walen, brought this suit under the Federal Tort Claims Act

(“FTCA”), 28 U.S.C. §§ 1346(b), 2674 et seq., and District of Columbia law against the United

States and the District of Columbia (the “District”) to recover for serious injuries she sustained

when a tree limb fell on her as she walked along Connecticut Avenue, a major pedestrian artery

in Northwest Washington. See Compl. ¶ ¶ 1–2, 7–8, ECF No. 1. On the day of the plaintiff’s

injury, Hurricane Sandy (“Sandy”) was affecting weather conditions in the District. The

plaintiff’s complaint alleges that the defendants owed a duty to maintain and inspect the trees

overlooking the relevant stretch of Connecticut Avenue, a bridge crossing the Klingle Valley, a

wooded depression in Rock Creek Park between the densely populated neighborhoods of

Woodley Park and Cleveland Park. See id. ¶¶ 19–20, 47–49. She also argues that the

defendants’ breaches of those duties—and not the storm—caused her injuries. See id. ¶¶ 21, 50.

She seeks $5,000,000 in compensatory damages, plus reasonable attorneys’ fees and costs. See

id. at 8, 13. Pending are the United States’ and District’s motions for summary judgment. See

D.C.’s Mot. Summ. J. (“D.C.’s Mot.”), ECF No. 43; U.S.’s Mot. Summ. J. (“U.S.’s Mot.”), ECF

No. 47. For the reasons that follow, both motions are denied.

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I. BACKGROUND

The factual and procedural background relevant to resolving the pending motions is

summarized below.

A. Factual Background

A tree limb fell on the plaintiff on October 29, 2012, at about 3:15 p.m. as she walked on

the sidewalk across the Connecticut Avenue Bridge (“the Bridge”), the portion of Connecticut

Avenue that spans the Klingle Valley. See United States’ Statement of Material Facts Not in

Dispute (“U.S.’s SMF”) ¶¶ 1–2, ECF No. 47-1, Defendant District of Columbia’s Statement of

Material Facts Not in Dispute (“D.C.’s SMF”) ¶ 17, ECF No. 43-1; Compl. ¶¶ 6–9. 1 She was

headed to pick up prescriptions at a pharmacy. See U.S.’s Mot., Ex. H, Dep. of Mary Lou Walen

(“Pl.’s Dep.”) at 33:1 to 33:6, ECF No. 47-10. The plaintiff has lost her memory of the incident,

see id., but another person walking on the Bridge at the time “heard a loud crashing sound,”

“turned toward the sound . . . [,] noticed that a tree branch had fallen,” and saw “a few people . . .

spinning toward the southwest side of the bridge.” Pl.’s D.C. Opp’n, Ex. H, Declaration of Eric

Kimbuende (“Kimbuende Decl.”) ¶ 4, ECF No. 49-7; see also Pl.’s Mem. Opp.’n Def. U.S.’s

Mot. Summ. J. (“Pl.’s U.S. Opp’n”), Ex. D, Kimbuende Decl. ¶ 4, ECF No. 50-3. “Upon

reaching them,” the witness, Eric Kimbuende, “noticed that a woman had been struck by the

branch.” Id.

1
In opposing the motions for summary judgment, the plaintiff, who is represented by counsel, failed to file
a “separate concise statement of genuine issues setting forth all material facts as to which it is contended there exists
a genuine issue necessary to be litigated,” as is required by the local rules, and thus “[i]n determining [the] motion
for summary judgment, the Court may assume that facts identified by the moving party in its statement of material
facts are admitted.” LCvR 7(h)(1); see also Grimes v. District of Columbia, 794 F.3d 83, 96–97 (D.C. Cir. 2015).
Nevertheless, here, the citations to the record found in the plaintiff’s briefing provided pointers to the disputed facts.
See Burke v. Gould, 286 F.3d 513, 518–19 (D.C. Cir. 2002) (leaving it to the district court to decide whether to
assume facts identified by the moving party are admitted); accord Arrington v. United States, 473 F.3d 329, 335
(D.C. Cir. 2006).

2
 The Metropolitan Police Department (“MPD”) arrived shortly thereafter, along with

emergency medical responders. See U.S.’s Mot., Ex. D, Metropolitan Police Dep’t, Police

Report (“MPD Report”) at 2, ECF No. 47-6. The MPD report of the incident stated that the

plaintiff “was on the public sidewalk on the west side of the 3200 block of Connecticut [Avenue]

NW when she was struck by falling tree limb. When the [responding officer] arrived on the

scene, he . . . observed fallen tree limb debris on and around [plaintiff].” Id. The plaintiff was

transported to George Washington University Hospital “in critical condition” and underwent

“emergency surgery.” Id.

“[T]rees under the maintenance jurisdiction of both” the National Park Service (“NPS”),

a federal agency, and the District overhang the Bridge. U.S.’s SMF ¶ 3 (citing U.S.’s Mot., Ex.

G, Dep. of Munevver Ertem (“Ertem Dep.”) at 9:5 to 10:11, ECF No. 47-9); see also Pl.’s Mem.

Opp.’n Def. D.C.’s Mot. Summ. J. (“Pl.’s D.C. Opp’n”), Ex. A., Ertem Dep. 9:5 to 10:11, ECF

No. 49-3. NPS maintains the trees in Klingle Valley because the Valley is part of a national

park, Rock Creek Park. U.S.’s SMF ¶ 2. A former D.C. Department of Transportation

(“DDOT”) road (now a trail) runs through the Valley, and the District shares with NPS

jurisdiction over the trees growing in the now-eroded road and in the road’s fifty-foot right of

way. Ertem Dep., at 9:5 to 10:11, ECF No. 47-9 and ECF No. 49-3. DDOT does not perform

routine inspections of trees in the Klingle Valley, relying instead on resident reports of obtrusive

or hazardous trees to trigger inspections and maintenance. See D.C.’s Mot., Ex. G., Ertem Dep.,

at 12:3 to 13:7, 16, ECF No. 43-1. NPS has protocols for routine tree inspections. See Pl.’s D.C.

Opp’n, Ex. F, Email from Tara Morrison, Superintendent, Rock Creek Park, to Richard Steacy,

Advisory Neighborhood Commission (Nov. 20, 2012) at 5, ECF No. 49-3; U.S.’s Mot., Ex. F,

Deposition of Donald Kirk (“Kirk Dep.”) at 21:3 to 24:24, ECF No. 47-8 (describing how NPS

3
prioritizes tree maintenance). In the pending motions, NPS’s protocols are less at issue than the

District’s.

A photograph of the Connecticut Avenue Bridge taken two days after the plaintiff was

injured, on October 31, 2012, by Diana Bramble, NPS’s supervisory horticulturalist for Rock

Creek Park, shows a several-foot-long pile of tree debris spanning half the width of the sidewalk.

See D.C.’s Mot., Ex. H, ECF No. 43-1. Visible atop the pile of debris is a red umbrella, which

the plaintiff has identified as her umbrella. Pl.’s D.C. Opp’n, Ex. G, Affidavit of Mary Lou

Walen (“Pl.’s Aff.”) ¶ 7, ECF No. 49-3; see also Pl.’s U.S. Opp’n, Ex. E, Pl.’s Aff. ¶ 7, ECF No.

50-3. Bramble also photographed a tree that had been uprooted at its base on the floor of the

Klingle Valley, beneath the Bridge. See D.C.’s Mot., Ex. I, ECF No. 1. Bramble testified that

she was “of the opinion that the debris on the bridge could possibly be from the large tree that

fell,” but she could not form a definitive opinion. D.C.’s Mot., Ex. B, Dep. of Diana Bramble

(“Bramble Dep.”) at 83:14 to 83:16. Kimbuende, the witness, attached to his declaration an

image of a tree immediately next to the bridge; the tree is missing a branch, and Kimbuende

states “it appears that the tree from which the branch fell is depicted . . . in the image.”

Kimbuende Decl. at ¶ 9.

The day of the plaintiff’s injury, Hurricane Sandy was affecting weather conditions in the

District. See D.C. SMF ¶¶ 1–10; U.S.’s SMF ¶¶ 7-16, 18; U.S.’s Mot., Ex. A, Nat’l Weather

Serv. Nat’l Hurricane Ctr., Tropical Cyclone Report Hurricane Sandy, AL12012, at 3–4, ECF

No. 47-3 (describing Sandy’s path on October 29); Pl.’s D.C. Opp’n, Ex. C., Nat’l Hurricane

Ctr., Sandy Graphics Archive, ECF No. 49-3 (showing Sandy’s location 216 miles from D.C. at

2:00 p.m. on October 29); Pl.’s U.S. Opp’n, Ex. B, Nat’l Hurricane Ctr., Sandy Graphics

4
Archive, ECF No. 50-3 (same as previous);2 Pl.’s D.C. Opp’n, Ex. E, Thomas E. Downs,

Meteorological Assessment Report (“Downs Report”) at 2–4, ECF No. 49-3 (“Hurricane Sandy

was approaching the East Coast of the United states on October 29, 2012.”); see also D.C.’s

Mot., Ex. L, Downs Report at 2–4, ECF No. 43-1 (same); Pl.’s U.S. Opp’n, Ex. A, Downs

Report, ECF No. 50-3 (same). The MPD report noted the weather conditions on the Bridge at

the time of the police response as “heavy rain and wind.” U.S.’s SMF ¶ 20 (citing MPD Report).

The parties dispute the precise weather conditions on the Bridge at the time of the injury.

Compare, e.g., Downs Report at 2, with U.S.’s SMF ¶¶ 7– 17 (describing the storm).

The following facts about the storm are not contested, however. Three days before the

accident, on October 26, 2012, the District’s then-Mayor Vincent Gray had declared a State of

Emergency “[b]ecause a storm system associated with Hurricane Sandy” was then “rapidly

approaching the District” and was “expected to have serious widespread effects in the region.”

D.C.’s Mot., Ex. A, Mayor’s Order 2012-186, “Declaration of Public Emergency,” (Oct. 26,

2012) (“D.C. Emergency Declaration”), ECF No. 43-1; see also U.S.’s SMF ¶ 10 (citing U.S.’s

Mot., Ex. B, D.C. Emergency Declaration, ECF No. 47-4); D.C.’s SMF ¶ 1. 3 At a press

conference on October 28, Gray cautioned D.C. residents to “shelter in place during the peak of

this storm.” U.S.’s SMF ¶ 13 (citing U.S.’s Mot., Ex. C., Press Release, D.C. Multi-Agency,

“Mayor Gray Closes District Government Monday,” Oct. 28, 2012 (“Press Release”), ECF No.

47-5); see also D.C.’s Mot., Ex. F, Tim Craig, Hurricane Sandy: D.C. Mayor Gray Calls for

Immediate Preparations, The Washington Post (Oct. 28, 2012), ECF No. 43-1 (recounting the

2
The plaintiff also attaches a Latitude/Longitude Calculator showing the measured distance between D.C.
and Hurricane Sandy’s location on the map in Exhibit C. See Pl.’s D.C. Opp’n, Ex. D., Nat’l Hurricane Ctr.,
Latitude/Longitude Calculator, ECF No. 49-3; Pl.’s U.S. Opp’n, Ex. C, Nat’l Hurricane Ctr., Latitude/Longitude
Calculator.
3
The State of Emergency declared by Mayor Gray ended on November 10, 2012. See D.C. Emergency
Declaration at 2 (explaining that the order remains in effect for fifteen days following its issuance on October 26).

5
press conference).4 Gray also said that the District “is likely to suffer significant power outages

due to fallen trees and other debris.” Press Release. The District’s press release issued about the

press conference stated that “the peak of the extreme winds [were] expected between about noon

Monday[, October 29] and the early hours of Tuesday morning.” Id.

Before her injury, the plaintiff “knew that there was a hurricane coming” on October 29

but was unaware that the Mayor had declared a State of Emergency. D.C.’s SMF ¶ 18 (quoting

D.C.’s Mot., Ex. J., Pl.’s Dep. at 67:6 to 67:23, ECF No. 43-1), ¶ 19 (citing Pl.’s Dep. at 68:16 to

68:21). When asked if she “recall[ed] if the news said when the hurricane would arrive,” the

plaintiff responded, “[t]hat evening”—that is, “[t]he evening of the 29th.” Id. at 68:23 to 69:9.

NPS facility manager for Rock Creek Park, Donald Kirk, testified that “Hurricane Sandy

brought a lot of trees down [in the Park].” D.C.’s Mot., Ex. C, Kirk Dep. at 44:5 to 44:6, ECF

No. 43-1. Bramble, the NPS horticulturalist, stated that the uprooted tree under the Bridge

“appeared to have fallen from the rain and heavy wind.” Bramble Dep. at 101:8–9. The plaintiff

has submitted an expert report by arborist Lew Bloch opining, after reviewing photographs of the

tree debris found on the Bridge and other evidence, that the limb on the Bridge “had been dead

or dying and decaying” for three to six years and that the limb “was large enough that it should

have been evident and discovered during tree risk assessment[s].” Bloch Report at 2.5

4
Also on October 28, 2012, Mayor Gray requested a Presidential Disaster Declaration for D.C., see D.C.’s
Mot., Ex. D, ECF No. 43-1; see also D.C.’s SMF ¶ 7, and the President declared that a major disaster existed in the
District on December 5, 2012, see D.C.’s Mot., Ex. E, FEMA Disaster Declaration FEMA-4096-DR, ECF No. 43-1;
see also D.C.’s SMF ¶ 8–9. These exhibits confirm Hurricane Sandy’s “widespread effects in the region.” D.C.
Emergency Declaration.
5
The plaintiff supplemented Bloch’s expert report with an affidavit from this same expert. See Pl.’s D.C.
Opp’n, Ex. I, Affidavit of Lew Bloch (“Bloch Aff.”), ECF No. 49-3; Pl.’s U.S. Opp’n, Ex. F, Bloch Aff. The
District objects that submission of this affidavit is untimely because plaintiff’s expert reports were due July 5, 2017
and the affidavit was submitted December 21, 2018. See D.C.’s Reply at 4. According to the District, the delay in
receiving the affidavit was “highly prejudicial,” requiring exclusion of the affidavit under Federal Rule of Evidence
37(c)(1), which “provides for the exclusion at trial of any information not disclosed pursuant to Rule 26(a), unless
the failure to disclose is harmless, or if there is substantial justification for such failure.” Halcomb v. Washington
Metro. Area Transit Auth., 526 F. Supp. 2d 24, 28 (D.D.C. 2007); see also FED. R. EVID. 37(c)(1). The District’s

6
 B. Procedural History

The plaintiff filed this suit in 2015. See Compl. at 1. The complaint alleges that D.C.

“has a duty to inspect and maintain its roads, sidewalks and trees so as to avoid risk of harm or

bodily injury,” id. ¶ 47, and that the United States “has a duty to inspect and maintain its parks,

trees and the surrounding environs so as to avoid the risk of harm or bodily injury,” id. ¶ 19. The

District allegedly breached its duty by “failing to exercise ordinary care in [the] inspection and

maintenance of roads, sidewalks and trees,” id. ¶ 48, and the United States allegedly breached its

duty by “failing to exercise ordinary care in its inspection and maintenance of Rock Creek Park

and its trees,” id. ¶ 20. Both defendants, the complaint says, negligently “fail[ed] to remove any

and all trees, limbs, branches and/or debris that posed a threat of harm or bodily injury in a

timely manner.” Id. ¶¶ 20 (Count I against United States), 48 (Count V against District).6 The

complaint “requests a trial by jury on all eligible claims.” Compl. at 14. By statute, “the court

without a jury” is the trier of fact in the action against the United States, 28 U.S.C. § 2402, but

the plaintiff’s claim against the District is eligible for a jury trial.

The United States’ motion to dismiss the claim against it for lack of subject matter

jurisdiction, see U.S.’s Mot. to Dismiss, ECF No. 14, was denied because the discretionary

function exception to the FTCA’s waiver of sovereign immunity did not apply when NPS’ tree

maintenance was governed by federal regulations “prescrib[ing] mandatory conduct for the

maintenance, inspection and record-keeping for trees in Rock Creek Park and further, to the

extent such actions are discretionary, implementation requires the application of scientific and

objection to the affidavit need not be resolved at summary judgment because, for the reasons explained below,
Bloch’s report is sufficient to withstand summary judgment without the supplemental affidavit.
6
The complaint also alleges that both defendants “fail[ed] to keep adequate records of inspection and
maintenance protocols for trees in [their] control,” Compl. ¶ 20, 48, but no reference to this negligent recordkeeping
theory appears in the plaintiff’s briefs.

7
professional judgment, not the weighing of policy factors underlying the discretionary function

exception,” Walen v. United States, 246 F. Supp. 3d 449, 457 (D.D.C. 2017). At the same time,

Walen dismissed counts of the complaint against several federal agencies, explaining that “the

FTCA provides the exclusive remedy for tortious conduct by the United States, which,

consequently, is the only properly named [federal] defendant.” Id. at 452 n.3.

Discovery then began and, following half a dozen extensions, lasted fifteen months. See

Min. Orders (Apr. 18, 2017; May 25, 2018; Sept. 12, 2017; Oct. 5, 2017; Dec. 1, 2017; Jan. 16,

2018; Apr. 13, 2018; May 25, 2018). The District’s and the United States’ motions for summary

judgment are now ripe for review.

II. LEGAL STANDARD

Summary judgment may be granted only if “there is no genuine dispute as to any material

fact and the movant is entitled to judgment as a matter of law.” FED. R. CIV. P. 56(a). “Material

facts are those that might affect the outcome of the suit under governing law; genuine issues are

those in which the evidence before the court is such that a reasonable trier of fact could find for

the moving party.” Hendricks v. Geithner, 568 F.3d 1008, 1012 (D.C. Cir. 2009); see also

Arrington, 473 F.3d at 333 (“A dispute over a material fact is ‘genuine’ if ‘the evidence is such

that a reasonable jury could return a verdict for the nonmoving party.’” (quoting Anderson v.

Liberty Lobby, Inc., 477 U.S. 242, 248 (1986)). The burden is on the moving party to

demonstrate that there is an “absence of a genuine issue of material fact” in dispute. Celotex

Corp. v. Catrett, 477 U.S. 317, 323 (1986); Hendricks, 568 F.3d at 1012.

In determining whether there is a genuine dispute for trial, a court must “view the

evidence in the light most favorable to [the non-moving party], draw all reasonable inferences in

[that party’s] favor, and may not ‘make credibility determinations or weigh the evidence.’”

8
Iyoha v. Architect of the Capitol, 927 F.3d 561, 565 (D.C. Cir. 2019) (quoting DeJesus v. WP

Co., 841 F.3d 527, 531 (D.C. Cir. 2016)). In the end, “a movant is entitled to summary judgment

when, drawing all inferences in favor of the non-movant, a reasonable jury could not return a

verdict in the non-movant’s favor.” Davis v. District of Columbia, 925 F.3d 1240, 1248 (D.C.

Cir. 2019) (citing Celotex, 477 U.S. at 326–27; Anderson, 477 U.S. at 248).

III. DISCUSSION

The District and the United States move separately for summary judgment on multiple,

and overlapping, grounds. See D.C.’s Mem. Supp. Mot. Summ. J. (“D.C.’s Mem.”) at 1–2, ECF

No. 43; U.S.’s Mem. Supp. Mot. Summ. J. (“U.S.’s Mem.”) at 1–2, ECF No. 47-2. To preview,

the District seeks summary judgment on three grounds: sovereign immunity, see D.C.’s Mem. at

10; the insufficiency of the plaintiff’s expert report to carry the plaintiff’s burden under D.C. law

to demonstrate the applicable standard of care, see id. at 14–21; and the operation of complete

defenses, including contributory negligence, assumption of risk, and act of God, D.C.’s Mem. at

9, 22–26. The United States’ motion builds on two of the District’s arguments, also attacking the

plaintiff’s expert report and raising the defense of contributory negligence. See U.S.’s Mem.

Supp. Mot. Summ. J. (“U.S.’s Mem.”) at 1–2, 8–12, 15, ECF No. 47-2.

Each of the defendants’ arguments is addressed in turn, with each applicable standard of

review presented before the analysis, starting with the District’s motion.

A. The District’s Motion for Summary Judgment

1. Sovereign Immunity

a) Applicable Legal Principles

The District asserts that sovereign immunity bars the claim against it because “the

District is immune from suit in tort if the act complained of was committed in the exercise of a

discretionary function,” D.C. Hous. Auth. v. Pinkney, 970 A.2d 854, 859 (D.C. 2009), and the

9
District classifies the “tree inspection and removal program []as discretionary in nature,” D.C.’s

Mem. at 10. The District acknowledges, id., that no immunity from suit is provided “where the

District’s conduct arises out of the exercise of ministerial powers” for which “there is a duty to

act in a reasonably safe and skillful manner,” Pinkney, 970 A.2d at 859 (quoting District of

Columbia v. Pace, 498 A.2d 226, 228 (D.C. 1985)); accord Nealon v. District of Columbia, 669

A.2d 685, 690 (D.C. 1995). “The determination of whether a governmental function is

discretionary or ministerial is one of law to be made by the trial judge,” Aguehounde v. District

of Columbia, 666 A.2d 443, 445 n.3 (D.C. 1995), and D.C. law places on the District the burden

of demonstrating that the function at issue in a suit is discretionary, see Barnhardt v. District of

Columbia, 8 A.3d 1206, 1214 (citing Aguehounde, 666 A.2d at 445 n.2).

The question of whether an action is discretionary “goes beyond whether the act entailed

a choice among alternatives. It seeks to ascertain whether the governmental action . . . allows

significant enough application of choice to justify official immunity, in order to ensure fearless,

vigorous and effective decision making.” Casco Marina Dev., L.L.C. v. D.C. Redevelopment

Land Agency, 834 A.2d 77, 81 (D.C. 2003) (quoting Moss v. Stockard, 580 A.2d 1011, 1020

(D.C.1990)). The general rule is that “discretionary acts involve the formulation of policy, while

ministerial acts involve the execution of policy.” Pinkney, 970 A.2d at 860 (quoting Nealon, 669

A.2d at 690)). “Discretionary acts have also been defined as acts that require personal

deliberation, decision and judgment. They generally have a broad public effect and call for a

delicate balancing of competing considerations.” Nealon, 669 A.2d at 690 (internal quotation

marks and citation omitted). “[M]inisterial acts require little or no judgment, and generally

constitute ‘mere obedience to orders or performance of a duty in which the [municipal employee]

10
has little or no choice.’” Id. (alteration in original) (quoting 18 E. McQuillin, MUNICIPAL

CORPORATIONS § 53.22.10 (3d ed. 1984)).

These definitions of discretionary and ministerial conduct under D.C. law have developed

greater concreteness in cases brought by plaintiffs injured on public roads and streets.7 On the

one hand, roadway “planning and design are discretionary functions.” Pace, 498 A.2d at 229

(citing Johnston v. District of Columbia, 118 U.S. 19, 20–21 (1886); District of Columbia v.

North Washington Neighbors, Inc., 367 A.2d 143, 148 n.7 (1976), cert. denied, 434 U.S. 823

(1977)). Thus, the District has been granted immunity from legal challenges to “the placement

of traffic control devices,” Pace, 498 A.2d at 229 (discussing Urow v. District of Columbia, 316

F.2d 351 (D.C. Cir.) (per curiam), cert denied, 375 U.S. 826 (1963)), and “bus stops,”

McKethean, 588 A.2d at 715; the “setting of yellow intervals” for traffic lights, Aguehounde, 666

A.2d at 451; as well as “freeway improvements,” Pace, 498 A.2d at 229. What these

discretionary, roadway-related functions have in common is that they are “complex, involving

the consideration of many competing factors and large expenditures of scarce resources,” id., and

so “[t]here is no reason to believe that the laymen on a jury are better qualified than the District’s

experts to render a decision on those matters,” id. at 230; see also, e.g., Urow, 316 F.2d at 352

(calling a city’s “general traffic control plan” “discretionary” and “quasi-legislative”).

On the other hand, “the District does have a ministerial duty to maintain its streets and

highways,” Pace, 498 A.2d at 230, where “maintenance means keeping the roadway and its

physical appurtenances in good condition, according to their original design,” id. at 231 (citing

7
In briefing whether the function at issue is discretionary, the plaintiff invokes primarily federal cases
defining the scope of the United States’ immunity under the FTCA. See Pl.’s D.C. Opp’n at 13–16. The FTCA, like
D.C. law, has a “discretionary function” exception, and D.C. courts occasionally rely on federal cases in developing
D.C. law. See, e.g., Aguehounde, 666 A.2d at 448; McKethean v. WMATA, 588 A.2d 708, 715 (D.C. 1991). No
D.C. case suggests that D.C. law and the FTCA are coterminous on this point, however.

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Wagshal v. District of Columbia, 216 A.2d 172, 172–74 (D.C. 1966); District of Columbia v.

Freeman, 477 A.2d 713, 715 (D.C. 1984)); see also Wagshal, 216 A.2d at 173 (“[I]t is well

established that an exception to the doctrine of sovereign immunity is the District's obligation to

maintain the streets in a reasonably safe condition for travel.” (citing Urow, 316 F.2d 351; Booth

v. District of Columbia, 241 F.2d 437 (D.C. Cir. 1956); District of Columbia v. Caton, 48 App.

D.C. 96 (1918)).

This distinction—between the discretionary functions of planning and design and the

ministerial function of maintenance—is rooted in over a century of case law defining the scope

of the District’s “duty . . . to maintain its streets ‘in a condition fit for convenient use and safe

against accident to travelers using them.’” Husovsky v. United States, 590 F.2d 944, 950 (D.C.

Cir. 1978) (quoting District of Columbia v. Woodbury, 136 U.S. 450, 463 (1890)); see also

Urow, 316 F.2d at 352 (calling this duty an “exception to the general rule of municipal immunity

with regard to the obligation to keep streets in a safe condition after being put on notice of a

defect”).8 For example, in 1886, in Johnston v. District of Columbia, 118 U.S. 19 (1886), the

Supreme Court explained that the District’s decisions about the planning and design of its sewer

system were discretionary but “for any negligence in . . . keeping [the sewer] in repair, . . . the

municipality . . . may be sued.” Id. at 21. D.C’s Court of Appeals has relied on cases like

Johnston in defining the scope of modern-day sovereign immunity. See Pace, 498 A.2d at 230–

31 (relying on such cases); Wagshal, 216 A.2d at 173 (same).

8
This duty applies not just to the District but to many municipalities. See McQuillin, supra, § 54.5
(“Generally concerning public ways, the judicial decisions or statutes have established and imposed these
obligations upon the municipal authorities: . . . [streets] must at all times be kept in proper repair or in a reasonably
safe condition insofar as may be by the exercise of ordinary diligence and continuous supervision . . . . The deeming
of the performance of these obligations not as a governmental duty but as a private or proprietary duty, such as a
ministerial function relating to corporate interests only, constitutes the reason, in some decisions, for imposing
municipal liability for injuries arising from defective public ways.”).

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 b) The District’s Claim to Immunity from this Suit

As noted, the District claims immunity from this suit “[b]ecause the District’s tree

inspection policy is discretionary.” D.C.’s Mem. at 13. Relying on deposition testimony by

DDOT Urban Forestry employee Munevver Ertem, the District defines this “tree inspection and

removal protocol” as a policy of “rel[ying] on resident reports and complaints” about dangerous

trees rather than “perform[ing] routine inspections of trees in the Klingle Valley.” D.C.’s Mem.

at 11 (citing Ertem Dep. at 12:3, 12:24 to 13:1; 16:8 to 16:10, ECF No. 43-1).9 In response to a

question whether the District had “any policies or procedures regarding routine inspections of the

[Connecticut Avenue] Bridge,” Ertem testified: “Routine inspections, no.” Ertem Dep. at 12:3–

6, ECF No. 43-1. Ertem further explained that “[r]esidents or anybody can request an

inspection,” id. at 12:24–25, and that after “there [has been] an inspection request,” a “picture[]

of the roadway[]” may be taken, id. at 16:5–10. Further, a DDOT inspection that reveals a

hazard could presumably lead to action to remedy that hazard. See id. at 16:21–25 (suggesting

that trees along roadways are sometimes trimmed). The District argues that the development and

application of its “tree inspection policy is discretionary,” D.C.’s Mem. at 13, likening that

policy to the formulation and implementation of a “plan of improvement” for a freeway, a

function the D.C. Court of Appeals deemed discretionary in Pace, D.C.’s Mem. at 12 (quoting

Pace, 498 A.2d at 229–30).10

9
The plaintiff argues that “the evidence suggests that DDOT’s Urban Forestry Division works concurrently
with NPS to remove trees within their concurrent jurisdiction” so that DDOT should be viewed as having the same
tree inspection policy as NPS. Pl.’s Opp’n at 14-15 (citing Ertem Dep. at 9:14 to 9:25, ECF No.49-2; Bramble Dep.
at 37:16 to 38:10). The two portions of the record cited by the plaintiff do not establish, however, that the District
follows NPS’s protocol. The cited portion of the Ertem Deposition merely delineates the District’s and NPS’s
jurisdiction and the cited portion of the Bramble deposition cannot be reviewed as this portion was not submitted as
an exhibit by any party.
10
Elsewhere, D.C. attempts to frame the function at issue as isolated from DDOT’s management of the
roads. See, e.g., D.C.’s Mem. at 12 (defining the function at issue without mentioning roads or sidewalks). Yet
Ertem’s testimony makes clear that DDOT’s tree inspection work cannot be so isolated. DDOT only inspects trees
when those trees interact with the “roadways”—“We take pictures of the roadways,” Ertem stated. Ertem Dep. at
16:15, ECF No. 43-1. The District later recognizes that the “issue of discretionary immunity” could be “control[led]

13
 The Ertem deposition testimony relied on by the District, see D.C.’s Mem. at 11 (citing

Ertem Dep. at 12:3; 12:2 -13:1; 16:8-16:10, ECF No. 43-1), defeats this analogy. Pace deemed

decisions about whether to make highway improvements discretionary because:

To hold otherwise would be effectively to impose a legal duty on
the District to have “state-of-the-art” streets. . . . The
implementation of evolving engineering standards is costly,
requiring the allocation of limited governmental funds through a
system of priorities. . . . Further, long-term planning in this area is
essential but would be thwarted entirely if it became the frequent
subject of litigation.

Id. The function, as described by Ertem, of inspecting and maintaining trees overhanging a long-

existing, major roadway is not similarly complex, specialized, or potentially frustrating to

municipal long-term planning.11

To the contrary, the conduct described by Ertem fits naturally into D.C. law’s definition

of ministerial road maintenance: “keeping the roadway and its physical appurtenances in good

condition, according to their original design.” Pace, 498 A.2d at 230. Analogy to a clear case of

road maintenance illustrates this. In Wagshal, a motorist sued the District claiming that a

downed stop sign had caused an accident in which he was injured. 216 A.2d at 173. The D.C.

Court of Appeals reasoned that the District would be immune from suit “for its failure to

establish a traffic control device at an intersection” and that D.C. “need not have put up the sign”

at issue “but [that] once it did, it had a duty to maintain it properly in order to keep the

intersection reasonably safe for motorists,” and could be sued for breach of that ministerial duty.

here” by the District’s “duty ‘to use reasonable diligence to protect motorists [and pedestrians near] . . . Klingle
Road,” and indeed all other roads, “from hazards posed by the land.’” D.C. Reply at 10 (quoting Husovsky, 590
F.2d at 953).
11
The other cases cited by the District do not help its claim of immunity. Nealon, 669 A.2d at 691, and
Chandler v. District of Columbia, 404 A.2d 964 (D.C. 1979), are both inapposite because they deal with fire
protection, and the law is well-established that “[a] municipality’s decision regarding fire protection is protected
from liability,” Nealon, 669 A.2d at 691 (citing Chandler, 404 A.2d at 966). Another case, Morgan v. District of
Columbia, 468 A.2d 1306, 1311 (D.C. 1983), also deals with a special rule of tort liability, the public duty doctrine,
which is not at issue in this case.

14
Id. at 174. The District is similarly not immune here, where the plaintiff claims not that the

District was negligent in its planning or design of the Connecticut Avenue Bridge but that the

District allowed a dangerous roadway condition to arise through negligence.

The District argues that the “formulat[ion] of the notice and inspection policy” was

discretionary because it involved weighing “such concerns as cost and the allocation of staff and

other resources.” D.C.’s Mem. at 11–12. Merely because conduct requires the allocation of

limited monetary or human resources does not make that conduct the exercise of a discretionary

function, however. See, e.g., Cope v. Scott, 45 F.3d 445, 449 (D.C. Cir. 1995) (“Budgetary

constraints . . . underlie virtually all government activity.” (quoting ARA Leisure Servs. v. United

States, 831 F.2d 193, 196 (9th Cir. 1987)). In Pinkney, for example, the D.C. Housing Authority

(“DCHA”) asserted that elevator replacement and maintenance in DCHA housing was

discretionary because it involved “budget-driven policy decision[s],” but the D.C. Court of

Appeals was unconvinced that this function “imposes upon [DCHA] determinations of such

delicacy and difficulty that its ability to furnish public [housing] will be ponderably impaired by

liability for neglect in failing to make such repairs.” 970 A. 2d at 862 (quoting Elgin v. District

of Columbia, 337 F.2d 152, 156–57 (D.C. Cir. 1964)). The same is true here: as already

explained, the District has long operated under a “duty . . . to maintain its streets ‘in a condition

fit for convenient use and safe against accident to travelers using them.’” Husovsky, 590 F.2d at

950 (quoting Woodbury, 136 U.S. at 463); see also e.g., Wagshal, 216 A.2d at 173 (“And

whether it be called governmental or ministerial, it is well established that an exception to the

doctrine of sovereign immunity is the District's obligation to maintain the streets in a reasonably

safe condition for travel.”).

15
 Finally, the District insists that this duty cannot “control[] here regarding the issue of

discretionary immunity,” D.C.’s Reply at 10, but points to reasons that go not to sovereign

immunity but to the sufficiency of the plaintiff’s evidence. As support, the District says that the

plaintiff’s expert arborist report is inadequate to “show that the District deviated from a duty of

‘reasonable diligence,’ or that its partial reliance on the United States to remove problem trees

from the Klingle Valley was unreasonable.” Id. The sufficiency of the plaintiff’s expert arborist

report, by Lew Bloch, is taken up next, and again with the United States’ motion.

2. Bloch’s Expert Report

a) Legal Principles Relevant to the Sufficiency of Bloch’s Report

“The plaintiff in a negligence action bears the burden of proof on three issues: ‘the

applicable standard of care, a deviation from that standard by the defendant, and a causal

relationship between that deviation and the plaintiff's injury.’” Toy v. District of Columbia, 549

A.2d 1, 6 (D.C. 1988) (quoting Meek v. Shepard, 484 A.2d 579, 581 (D.C. 1984)). Under D.C.

law, “[a] plaintiff must put on expert testimony to establish what the standard of care is if the

subject in question is so distinctly related to some science, profession or occupation as to be

beyond the ken of the average person.” District of Columbia v. Arnold & Porter, 756 A.2d 427,

433 (D.C. 2000) (quoting Messina v. District of Columbia, 663 A.2d 535, 538 (D.C. 1995));

accord, e.g., Varner v. D.C., 891 A.2d 260, 267 (D.C. 2006); see also Briggs v. WMATA., 481

F.3d 839, 845 (D.C. Cir. 2007) (collecting examples). Consequently, allegations of negligent

maintenance of trees must be supported by expert testimony. Briggs, 481 F.3d at 845 (discussing

Katkish v. District of Columbia, 763 A.2d 703, 706 (D.C. 2000) (requiring expert testimony to

establish when the condition of a “tree may create a dangerous situation requiring a[] . . .

response and whether the likelihood of the tree falling is related to the condition of the tree, the

16
street, or other circumstances,” Katkish, 763 A.2d at 706). The parties thus agree “that this

matter requires expert testimony demonstrating the applicable standard of care.” Pl.’s Opp.’n at

16; see also D.C.’s Mem. at 14–15; U.S.’s Mem. at 13.

At trial, expert testimony on standard of care must identify a “concrete standard upon

which a finding of negligence could be based.” District of Columbia v. Carmichael, 577 A.2d

312, 315 (D.C. 1990). “[G]eneralized references” to standards are insufficient. District of

Columbia v. Moreno, 647 A.2d 396, 400 (D.C. 1994); see also Phillips v. District of Columbia,

714 A.2d 768, 773 (D.C. 1988) (“[T]he expert must testify as to specific . . . standards.”). This

means, as the D.C. Circuit has explained, that, under D.C. law, an expert’s trial testimony “is not

sufficient if it consists merely of the expert’s opinion as to what he or she would do under similar

circumstances,” or if “the expert simply . . . declare[s] that the [defendant] violated the national

standard of care.” Briggs, 481 F.3d at 846 (third alteration in original) (quoting Clark v. District

of Columbia, 708 A.2d 632, 635 (D.C. 1997)). “Rather, the expert must clearly articulate and

reference a standard of care by which the defendant’s actions can be measured” and “clearly

relate the standard of care to the practices in fact generally followed by other comparable . . .

facilities or to some standard nationally recognized by such units.” Id.; see also, e.g., Travers v.

District of Columbia, 672 A.2d 566, 569 (D.C. 1996) (requiring “evidence that a particular

[standard] is followed nationally”).

The procedural posture of the litigation at the time of assessing the sufficiency of the

expert’s articulation of the standard of care is significant. “[C]ourts have recognized that there is

a lower standard for an expert’s identification of a national standard of care when considered at

the summary judgment stage than when the expert’s testimony is considered in the directed

verdict context, after the expert has testified.” Pauline v. United States, 962 F. Supp. 2d 301,

17
303 (D.D.C. 2013); see also Liser v. Smith, 254 F. Supp. 2d 89, 103–04 (D.D.C. 2003); Robinson

v. WMATA, 858 F. Supp. 2d 33, 41 n.7 (D.D.C. 2012). Accordingly, at summary judgment, “the

plaintiff’s experts must assert only ‘a colorable basis to believe that [the expert’s] testimony may

satisfy’ the standard for identifying the national standards of care and linking an expert’s opinion

to them.” Pauline, 962 F. Supp. 2d at 303 (quoting Liser, 254 F. Supp. at 103–04); see also

Snyder v. George Washington Univ., 890 A.2d 237, 246 (D.C. 2006) (deeming expert report

sufficient at summary judgment because it “reflected evidence of a national standard and was

‘not . . . based upon [his own] personal opinion, nor mere speculation or conjecture’” (quoting

Hawes v. Chua, 769 A.2d 797, 806 (D.C. 2001)); Pannell v. District of Columbia, 829 A.2d 474,

479 (D.C. 2003) (stating that report “was insufficient to withstand . . . summary judgment”

where expert witness “failed to offer any support for his conclusion that the District violated a

national standard of care”); Varner, 891 A.2d at 269 (rejecting expert testimony at summary

judgment because “[o]ther than his own personal opinion,” the expert was “unable to suggest any

recognized standard, written or oral, which addressed the” standard of care).

b) Sufficiency of Bloch’s Report

Lew Bloch, the plaintiff’s expert arborist, reviewed “color photographs” of a fallen tree

on the Connecticut Avenue Bridge, NPS documents “related to tree management,” an email

exchange between the Superintendent of Rock Creek Park and a member of the area Advisory

Neighborhood Commission, as well as the MPD report about the incident that injured plaintiff.

See Bloch Report at 2, 4–12. Based on NPS “documents” (naming “[t]heir A-123 Internal

Control Assessment Program and Tree Management Action Plan”) and based on statements by

the Superintendent in the emails, Bloch concludes that “regular inspections are required by

NPS”—“monthly drive-by inspections for primary roads, bi-annual walk through inspections for

all other areas by trained tree care professionals.” Bloch Report at 2. Bloch adds that the

18
documents state that these inspections are required to “maintain[] safety of the public from

hazardous trees.” Id. In Bloch’s “professional opinion,” the limb in the images he reviewed

“had been dead or dying and decaying” for three to six years and the limb “was large enough that

it should have been evident and discovered during tree risk assessment[s].” Id. Explaining this

opinion, Bloch reports that the “pieces” of the fallen limb on the sidewalk “were so brittle and

decayed that they shattered when they landed. If this had been a live limb that fell, it would not

have broken up in such small pieces.” Id. The report finally certifies that Bloch’s “opinions and

conclusions were developed, and this report prepared in conformity with standard arboricultural

practices, and my expertise as a consulting arborist.” Id. at 3.

Whether Bloch’s current report would satisfy the standard for expert trial testimony is not

at issue here. As already explained, at this stage, the standard that Bloch’s report must meet is a

less demanding one. Bloch’s report survives because the standard of care articulated there is

neither overly general nor dependent on totally baseless assertions. The cases applying D.C.’s

expert testimony requirement at the summary judgment stage emphasize that those are the two

flaws that can be fatal. See Liser, 254 F. Supp. 2d at 103 (“[T]his is not a situation where the

expert’s reports . . . are completely devoid of any reference to concrete and specific standards or

practices.”). In Briggs, for example, the D.C. Circuit, applying D.C. law, rejected expert

testimony because it was “both too general and too vague to satisfy the requirements of D.C.

law.” 481 F.3d at 846. In the cases in which the D.C. Court of Appeals has rejected, at summary

judgment, expert testimony establishing the standard of care, the experts offered either no

opinion about the relevant standard or no basis for their opinion. In one, the expert, at his first

deposition, testified that he had no “opinion as to whether” certain defendants “met the national

standard of care” and, at his second deposition, “failed to offer any support for his conclusion

19
that the District violated a national standard of care.” Pannell, 829 A.2d at 479. In another,

“[o]ther than his own personal opinion,” the expert was “unable to suggest any recognized

standard, written or oral, which addressed the question” of standard of care. Varner, 891 A.2d at

269.12 In contrast, when viewed in the light most favorable to the plaintiff, the specifics in

Bloch’s report describing the frequency and nature of inspections required by NPS and the

appearance and size of the limb indicate that Bloch may, at trial, provide a non-expert trier of

fact with a concrete, specific standard of care regarding tree inspections and what such

inspections should have identified.

The District criticizes Bloch’s report for making “no mention of the District or DDOT at

all,” D.C.’s Mem. at 17; see also D.C.’s Reply at 5, but that omission is not fatal to plaintiff’s

claim against the District. No legal authority is cited by the District requiring that each

defendant must be mentioned in an expert report establishing the relevant standard of care.

Further, the D.C. law is clear that “an expert may support a purported standard by showing that it

has been accepted as controlling in facilities and enterprises that are similar to defendants’

facilities or enterprises.” Briggs, 481 F.3d at 847 (citing Clark, 708 A.2d at 635; Messina, 663

A2d at 539; Toy, 549 A.2d at 8); cf. Snyder, 890 A.2d 237 (“The fact that [the expert] did not

expressly use the words ‘national standard’ when stating his expert opinion does not, in itself,

render his opinion inadmissible.”). Given this, Bloch’s report satisfies the threshold for

sufficiency at summary judgment by analyzing the tree protocols of similar “facilities or

enterprises,” like NPS. Finally, Bloch’s opinion is that the tree limb would not have fallen on the

plaintiff had tree inspections of the sort described in the NPS protocols occurred. The logic of

that conclusion does not depend on an analysis of DDOT’s policies. See Liser, 254 F. Supp. 2d

12
The third case is one in which the plaintiff had failed to offer any expert testimony at all. See Jones v.
Nat'l R.R. Passenger Corp., 942 A.2d 1103, 1108 (D.C. 2008).

20
at 103 (deeming sufficient to survive summary judgment an expert report asserting that the

plaintiff’s injury would have been avoided had investigators followed “the standard of care

delineated” in the expert report).

The District argues at length, yet without citation to any legal authority, that Bloch’s

report has “fatal flaws” in its factual bases and that those flaws require his testimony to be

excluded from trial. Specifically, the District faults Bloch’s report as based on “photographs

taken after Plaintiff was removed from the accident showing (a) tree parts, and (b) a tree that has

a missing limb,” contending this “is simply not enough to establish that the tree with the missing

limb shed a limb that struck Plaintiff.” D.C.’s Mem. at 21. Additional faults cited by the District

are that Bloch failed “to supply the ‘whys and wherefores’ for his opinions,” to “consider the

deposition testimony taken during discovery,” or “to explain why he believes that the debris on

the bridge shows the tree that struck Plaintiff.” Id. The United States raises overlapping

objections supplemented with legal citations, so these objections are addressed with the United

States’ motion. See infra in Part III.B.1. As explained there, Bloch’s testimony meets the basic

threshold for admissibility, so these objections must be assessed at a later stage. See Daubert v.

Merrell Dow Pharm., Inc., 509 U.S. 579, 596 (1993) (“[V]igorous cross examination,

presentation of contrary evidence, and careful instruction on the burden of proof are the

traditional and appropriate means of attacking shaky but admissible evidence”); Ambrosini v.

Labarraque, 101 F.3d 129, 138, 141 (D.C. Cir. 1996) (explaining that “credibility” and

“persuasiveness” are not “gatekeeper” issues but rather issues of “the weight appropriately to be

accorded such testimony by a fact finder”).

21
 3. Defenses

The District raises three defenses, any of which, if successful, would bar the plaintiff’s

claim. As discussed next, however, issues of material fact preclude summary judgment for the

District on any of these defenses.

a) Act of God Defense

“An Act of God is the result of the direct, immediate and exclusive operation of the

forces of nature, uncontrolled or uninfluenced by the power of man and without human

intervention, and is of such character that it could not have been prevented or avoided by

foresight or prudence.” Watts v. Smith, 226 A.2d 160, 162 (D.C. 1967). “Extraordinary floods,

storms of unusual violence, sudden tempests, severe frosts, great droughts, lightnings,

earthquakes, sudden deaths and illnesses, have been held to be ‘acts of God.’” Gleeson v. Va.

Midland Ry. Co., 140 U.S. 435, 439 (1891). Ordinary storms and typical rainfall are not acts of

God. Shea-S&M Ball v. Massman-Kiewit-Early, 606 F.2d 1245, 1249 (D.C. Cir. 1979) (“Heavy

rainfalls, unless they are unusual and extraordinary, are not considered acts of God.”). “[H]uman

intervention” or contribution bars an act of God defense “when the effect, the cause of which is

to be considered, is found to be in part the result of the participation of man, whether it be from

active intervention or neglect.” Fred Drew Constr. Co. v. Mire, 89 A.2d 634, 636 (D.C. Cir.

1952).

To prevail on summary judgment on an act of God defense, then, the District must show

that, as a matter of law, an exceptional or extraordinary natural phenomenon, absent human

contribution, caused the plaintiff’s injury. The District argues that the undisputed facts establish

(1) that Hurricane Sandy was such a phenomenon, see D.C.’s Mem. at 4–7, and (2) that “[t]he

District did not contribute to Plaintiff’s injury,” D.C.’s Mem. at 7. Genuine issues for trial are

present as to both prongs necessary to sustain this act of God defense.

22
 First, and briefly, the District’s act of God defense fails because it cannot be said on this

record that, as a matter of law, “human intervention”—relevantly, negligence by the District—

contributed not at all to the limb’s fall. Contrary to the District’s position that “there is no

competent evidence in the record in this case that indicates negligence by the District in the

maintenance or inspection of the tree that struck Plaintiff,” D.C.’s Mem. 7, Bloch’s expert report

opines that the limb would not have fallen but for negligence by a human actor, see Bloch Report

at 2–3.

Second, and more importantly, a clear factual dispute is presented over whether the

weather conditions at the time of the plaintiff’s injury were “extraordinary” or “unusual[ly]

violent.” Gleeson, 140 U.S. at 439. The plaintiff retained a meteorological expert, Thomas

Downs, who concluded: “To a reasonable degree of meteorological certainty, at the subject

[Bridge] and at the time of the incident, October 29, 2012 at about 3:15 p.m., skies were

overcast, rain was falling with a temperature of around 52°F and the wind was out of the

northwest around 28 mph with gusts up to 40 mph.” Downs Report at 1. News-outlet weather

reports offered by the District help contextualize Downs’ findings. One describes “[w]inds . . .

sustained at around 20 mph, with some gusts over 30 mph” as “not too bad.” D.C.’s Mem. at 6

(quoting Dan Stillman, D.C. area forecast, The Washington Post (October 29, 2012),

https://www.washingtonpost.com/blogs/capital-weather-gang/post/dc-area-forecast-sandy-

power-slams-the-nations-capital-downed-trees-dangerous-travel-conditions-and-power-outages-

imminent/2012/10/29/644231ce-216d-11e2-ac85-e669876c6a24_blog.html?utm_term=

.bfeb6a02eee7). Another states that, later in the day, “as we get toward sunset, there is a good

chance for at least areas of sustained winds near or above tropical storm force, with gusts

potentially approaching 70-80 mph.” Id. (quoting Ian Livingston, Winds increasing in D.C. area

23
as Sandy approaches, worst arrives around evening, The Washington Post (October 29, 2012),

https://www.washingtonpost. com/blogs/capital-weather-gang/post/winds-increasing-in-dc-area-

as-sandy-approaches-worst-arrives-around-evening/2012/10/29/dc9302cc-21e8-11e2-ac85-

e669876c6a24_blog.html?utm_term=.8fe6dda21c07 (“Livingston Blog Post”)).13

The District disputes Downs’ conclusion by pointing to two types of evidence: (1) Mayor

Gray’s declaration of a State of Emergency on October 26 and Gray’s request to the President for

a Presidential Disaster declaration, D.C. Mem. at 5; and (2) weather predictions and post-storm

reports from the Washington Post’s meteorologists, id. at 4–7.14 As to the latter evidence, for

example, the District notes that, about two hours before the plaintiff’s injury, at 1:17 PM, a

meteorologist at the Washington Post blogged: “Winds across D.C. area are currently sustained

in the 25 to 35 mph range, with gusts near and past 40 mph.” Id. at 6 (quoting Livingston Blog

Post).15 After the storm, the Washington Post reported that wind gusts on October 29 had peaked

at 55-65 mph and that 3.85” of rain had fallen, “a precipitation record for that day of the year.”

Id. at 7 (citing Jason Samenow, Was Hurricane Sandy well-forecast?, The Washington Post

(October 30, 2012), https://www.washingtonpost.com/blogs/capital-weather-gang/post/was-

13
The District does not challenge Downs’ meteorological findings, but argues that “[d]ata provided by . . .
Downs . . . totally contradicts Plaintiff’s argument that Plaintiff chose to walk outside during a period of ‘average
rainfall and wind speed,’ or that ‘the storm had not actually begun to manifest in the D.C. area at the time of
Plaintiff’s injury.’” D.C. Reply at 8. The proper interpretation of the data provided by Downs is a dispute for trial.
See, e.g., Heller v. District of Columbia, 952 F. Supp. 2d 133, 142 (D.D.C. 2013) (explaining that “concerns about
the conclusions” of experts are issues for trial and collecting cases).
14
The District also challenges Downs’ different conclusion that the winds at around 3:15 pm were below or
“near the lower bound of” the threshold at which “healthy tree[]” branches would be expected to break from wind
damage. Downs Report at 4. D.C. objects first that “Downs is not qualified to opine on the impact of sustained high
winds on trees,” D.C. Reply at 8, and second that this conclusion is incorrect, based on the report of the District’s
own expert arborist, see D.C.’s Reply at 8 (citing Attachment A, Expert Rebuttal Report by Mark Webber, ECF No.
53). Even if this challenged conclusion by Downs is not considered, however, the plaintiff’s claims survive
summary judgment. Thus, the District’s objections to Downs’ conclusion about the health of the broken tree need
not be resolved at this stage.
15
The District also cites a webpage showing that, at 2:52 p.m., Ronald Reagan Washington National
Airport’s weather station reported 23 mph sustained wind and 45 mph gusts. See Weather Underground, Ronald
Reagan Washington National, VA: Daily Observations (October 29, 2012), https://www.wunderground.com/history/
daily/KDCA/date/2012-1029?req_city=Washington&req_state=DC&req_ statename=District%20of%20Columbia
&reqdb.zip=20008&reqdb.magic=1&reqdb.wmo=99999.

24
hurricane-sandy-well-forecast-was-it-over-hyped/2012/10/30/67075e52-22c1-11e2-ac85-

e669876c6a24_blog.html?utm_term=.c19039715898; Justin Greiser, Hurricane Sandy recap:

Historic storm from storm surge to snow, The Washington Post (October 31, 2012),

https://www.washingtonpost.com/blogs/capital-weather-gang/post/hurricane-sandy-recap-

historic-storm-from-storm-surge-to-snow/2012/10/31/9a7c56d8-2362-11e2-ac85-

e669876c6a24_blog.html)). This dueling evidence creates a dispute, one which must be resolved

by a trier of fact, about whether the weather conditions at the time were “extraordinary and

unusual” enough to qualify those conditions as an act of God. Shea-S&M Ball, 606 F.2d at 1249.

The same factual dispute precludes summary judgment for the District on its contributory

negligence defense.

b) Contributory Negligence

Contributory negligence is “the failure to act with the prudence demanded of an ordinary

reasonable person under like circumstances.” Stager v. Schneider, 494 A.2d 1307, 1311 (D.C.

1985). In D.C., when a plaintiff’s contributory negligence is a “factor” contributing to the

plaintiff’s injury, the plaintiff may not recover at all against the defendant. George Washington

Univ. v. Waas, 648 A. 2d 178, 180 (D.C. 1994) (quoting Sinai, 498 A.2d at 528); see also, e.g.,

Andrews v. Wilkins, 934 F.2d 1267, 1272 (D.C. Cir. 1991).16 This is true “even if the defendant

was also negligent.” Sinai, 498 A.2d at 528. “A party asserting the defense of contributory

negligence is required to establish, by a preponderance of the evidence, that the plaintiff failed to

exercise reasonable care,” Poyner v. Loftus, 694 A.2d 69, 71 (D.C. 1997), and a plaintiff is

16
The phrase “substantial factor” is sometimes used, see, e.g., Sinai v. Polinger Co., 498 A.2d 520, 528
(D.C. 1985), but this modifier may be misleading, as the issue is not one of degree—“[t]he rule is simply that
contributory negligence bars a plaintiff’s recovery,” Wingfield v. Peoples Drug Store, Inc., 379 A.2d 685, 687 (D.C.
1977) (citing Karma Constr. Co. v. King, 296 A.2d 604, 605 (D.C. 1972)).

25
negligent when she “was unreasonable in encountering a known risk or a risk of which [s]he

should have been aware,” Sinai, 498 A.2d at 525.

“Ordinarily, questions of negligence and contributory negligence must be decided by the

trier of fact.” Poyner, 694 A.2d at 71 (citing Washington v. A. & H. Garcias Trash Hauling Co.,

584 A.2d 544, 545 (D.C. 1990)). Only “where the evidence, taken in the light most favorable to

the plaintiff, establishes contributory negligence so clearly that no other inference can reasonably

be drawn,” should contributory negligence be decided as a matter of law at summary judgment.

Id. (citing District of Columbia v. Brown, 589 A.2d 384, 387–88 (D.C. 1991)). And “[o]nly in

the exceptional case is evidence so clear and unambiguous . . . .” Tilghman v. Johnson, 513 A.2d

1350, 1351 (D.C. 1986).

The factual dispute over the precise weather conditions on the Bridge the afternoon of the

plaintiff’s injury dooms D.C.’s argument that “Plaintiff’s decision to walk across a high bridge

surrounded by trees during a storm constitutes contributory negligence” as a matter of law.

D.C.’s Mem. at 24. That dispute is obviously material to whether an ordinary reasonable person

would have walked down Connecticut Avenue “under like circumstances.” Stager, 494 A.2d at

1311. Another fact deepens the dispute: as the plaintiff emphasizes, citing the declaration of

Kimbuende, the witness, multiple other people were on the Bridge with her. See Pl.’s D.C.

Opp’n at 23 (citing Kimbuende Decl.). This fact undermines the District’s inference that the

plaintiff’s decision to go to the pharmacy that afternoon was unreasonable.

The District likens this case to Phillips v. Fujitec America, Inc., 3 A.3d 324 (D.C. 2010),

but Phillips involved no similar disputes. There, the plaintiff fell down an elevator shaft while

attempting to crawl out a gap in the doors of a disabled elevator, ignoring admonitions not to

attempt this. Id. at 326 & n.2. The parties in Phillips did not dispute the conditions that created

26
a risk of injury, and the absence of such a dispute, as well as the obvious (and warned-of) nature

of the risk, made possible the conclusion that the plaintiff had been contributorily negligent as a

matter of law. See id. at 329–30 & n.16 (explaining that, even though “[t]ypically,

reasonableness is a question for the jury,” this type of “fact pattern” involving undisputed facts

and clear warnings, allowed for resolution of contributory negligence at summary judgment, id.

at 329 n.16). Here, in contrast, the underlying conditions and the level of risk are disputed.

D.C. also suggests that the declared State of Emergency made it unreasonable as a matter

of law for the plaintiff to go outside. See D.C.’s Mem. at 23, 25 (referencing the state of

emergency). The United States makes a more sustained argument in this vein, so the point is

considered with the United States’ motion.

c) Assumption of Risk

“The defenses of contributory negligence and assumption of risk may be viewed as

‘intersecting circles, with a considerable area in common.’” Sinai, 498 A.2d at 524 (quoting W.

Prosser & W. Keeton, LAW OF TORTS § 68, at 481 (5th ed. 1984)). The elements of assumption

of risk are, first, subjective “knowledge of the danger and second, a voluntary exposure to that

known danger.” Dougherty v. Chas. H. Tompkins Co., 240 F.2d 34, 35–36 (D.C. Cir. 1957).

While contributory negligence turns on what the plaintiff should have known, assumption of risk

turns on what the plaintiff did know; as a result, while contributory negligence focuses on

reasonableness, assumption of risk focuses on voluntariness. See Phillips, 3 A.3d at 328.

The District’s assumption of the risk defense fails for two reasons. First, under D.C. law,

when the question is whether “the plaintiff voluntarily but unreasonably accept[ed] a known risk

created by the defendant’s negligence, either defense could theoretically apply,” but the D.C.

Court of Appeals has—“in keeping with the Restatement (Second) of Torts—chose[n] to analyze

such ‘hybrids’ as contributory negligence cases.” Phillips, 3 A.3d at 328 (discussing Scoggins v.

27
Jude, 419 A.2d 999, 1004 (D.C. 1980)). Here, D.C. posits that the plaintiff “understood the risk

of the storm” and chose to go out anyway, D.C. Mem. at 26, thereby placing this case in the

“hybrid” category, see Harris v. Plummer, 190 A.2d 98, 100 (D.C. 1963) (“Assumption of risk

involves voluntary or deliberate incurring of a known danger; contributory negligence generally

involves inadvertence or failure to observe or act.”); see also Scoggins, 419 A.2d at 1004–05

(similar). Thus, the proper defense to consider is contributory negligence. The District is not

entitled to summary judgment on its contributory negligence defense for the reasons already

stated. See supra in Part III.A.3.b.

Second, the proffered assumption of risk defense fails because the record does not

establish as a matter of law that the plaintiff had the requisite subjective knowledge. “[T]he

plaintiff must subjectively know of the existence of the risk and appreciate its unreasonable

character.” Sinai, 498 A.2d 520, 524 (D.C. 1985) (citing Restatement (Second) of Torts § 496D

(1965)). To be sure, the plaintiff stated in her deposition that she “knew that there was a

hurricane coming.” Pl.’s Dep. at 67:23. Yet, when asked if she “recall[ed] if the news said when

the hurricane would arrive,” the plaintiff responded, “[t]hat evening”—that is, “[t]he evening of

the 29th.” Id. at 68:23 to 69:9 (emphasis added). That testimony could suggest to a trier of fact

that the plaintiff was unaware of any unusual danger that afternoon. Finally, as the District

acknowledges, see D.C. Mem. at 26, the plaintiff also testified that she was unaware that the

Mayor had declared a State of Emergency, Pl.’s Dep. at 68:16 to 68:21. This aspect of her

testimony further suggests that she did not understand there to be any serious danger that

afternoon. In short, the plaintiff’s own testimony about her subjective knowledge makes it

impossible to hold that she assumed the risk as a matter of law.

The United States’ motion is considered next.

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 B. The United States’ Motion for Summary Judgment

The United States contends that it is entitled to summary judgment on two grounds. First,

the United States argues that Bloch’s report “fails to meet the standard required for competent

expert testimony in a liability case” and, as a result, is inadmissible at trial to establish the

relevant standard of care. See U.S.’s Mem. at 15. Second, the United States claims that the

plaintiff was contributorily negligent as a matter of law because she did not “adhere to

emergency management warnings.” U.S.’s Mem. at 8–12. Neither contention is persuasive.

1. Bloch’s Report

a) Legal Principles Relevant to the Admissibility of Bloch’s Report

Before expert testimony may be admitted at trial, Federal Rule of Evidence 702 and the

Supreme Court’s decision in Daubert require a district court to act as “gatekeep[er]” by

“engag[ing] in a preliminary assessment of the scientific validity of the expert’s reasoning or

methodology.” Ambrosini, 101 F.3d at 138 n.11 (citing Daubert, 509 U.S. at 592–93); see also

FED. R. EVID. 702; United States ex rel Miller v. Bill Harbert Int’l Const., Inc., 608 F.3d 871,

894 (D.C. Cir. 2010) (“[T]rial judges must act as gatekeepers to exclude unreliable expert

testimony.”). Those rules require the party seeking to introduce the expert testimony to

establish, by a preponderance of the evidence, the qualifications of the proffered expert and that:

“(a) the expert’s scientific, technical, or other specialized knowledge will help the trier of fact to

understand the evidence or to determine a fact in issue; (b) the testimony is based on sufficient

facts or data; (c) the testimony is the product of reliable principles and methods; and (d) the

expert has reliably applied the principles and methods to the facts of the case.” FED. R. EVID.

702; see also United States v. Hite, 769 F.3d 1154, 1168 (D.C. Cir. 2014) (“Expert testimony is

admissible under Federal Rule of Evidence 702 if it will assist the jury ‘to understand the

29
evidence or determine a fact in issue.’” (quoting FED. R. EVID. 702(a)). In other words, the party

offering the expert need not prove that the expert’s opinions are correct but rather that the expert

is a qualified person who has reached his opinions in a methodologically reasonable manner. See

Ambrosini, 101 F.3d at 133 (explaining that courts “must focus solely on principles and

methodology, not on the conclusions that they generate” (quoting Daubert, 509 U.S. at 595)); see

also Kumho Tire Co. Ltd. v. Carmichael, 526 U.S. 137, 152–53 (1999) (stating that the trial

court’s job “is to make certain that an expert, whether basing testimony upon professional studies

or personal experience, employs in the courtroom the same level of intellectual rigor that

characterizes the practice of an expert in the relevant field”).

Daubert motions are motions in limine, but “[t]he Daubert regime can play a role during

the summary judgment phase of civil litigation.” Cortés-Irizarry v. Corporación Insular de

Seguros, 111 F.3d 184, 188 (1st Cir. 1997); see also Crowley v. Purdue, 318 F. Supp. 3d 277,

291–92 (D.D.C. 2018) (citing Carmichael v. West, No. 12-cv-1969, 2015 WL 10568893, at *7

(D.D.C. Aug. 31, 2015)); 4 Jack B. Weinstein & Margaret A Berger, WEINSTEIN’S FEDERAL

EVIDENCE, § 702.05[4] (Joseph M. McLaughlin, ed., Matthew Bender 2d ed. 2013). A court

“must be cautious—except when defects are obvious on the face of a proffer—not to exclude

debatable scientific evidence [at summary judgment] without affording the proponent of the

evidence adequate opportunity to defend its admissibility.” Cortés-Irizarry, 111 F.3d at 188.17

“In sum, the [U.S.] faces a steep burden to exclude expert testimony at this stage in the

litigation.” D.L. v. District of Columbia., 109 F. Supp. 3d 12, 28 (D.D.C. 2015).

17
“Holding an evidentiary/Daubert hearing at the summary judgment stage would assuage any concern, but
no evidentiary/Daubert hearing has yet been requested or held in this case.” Carmichael, 2015 WL 10568893 at *7
(internal citations omitted).

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 b) Admissibility of Bloch’s Report

The United States acknowledges that excluding the Block Report at this stage of the

litigation poses a difficult burden but nonetheless asserts that there should be “little difficulty in

finding that Plaintiff’s proffered exp[e]rt report clearly fails to meet the standard required for

competent expert testimony in a liability case” because “Plaintiff’s expert provides no

methodology whatsoever in how he came to” his conclusions. U.S.’s Mem. at 15. On

inspection, the United States’ objections are misplaced, and Bloch’s expert testimony meets the

standard for admissibility for the purposes of summary judgment.

Two of the United States’ attacks on the report are red herrings. The United States

observes that “Plaintiff’s expert does not opine on where the limb came from . . . .” U.S.’s Mem.

at 16. It also argues that Bloch does not “discuss the weather conditions experienced at the time

of the accident,” id., even though Bloch does conclude that a healthy limb would not have “failed

from the weather events,” Bloch Report at 3. At the same time, the United States makes no

showing that consideration of these features of the incident is essential to establishing the

standard of care, or breach of that standard, in a methodologically reasonable manner. Although

Bloch’s failure to address these facts in his short, two-page report certainly makes the report’s

conclusions less believable, “believability” is an issue that can be “appropriately addressed

through cross-examination.” Heller, 952 F. Supp. 2d at 142 (collecting cases); see also, e.g.,

Daubert, 509 U.S. at 596 (citing various elements of the “adversary system” as “appropriate

safeguards” against “shaky but admissible evidence”).

The United States’ other objections similarly “conflate[] the questions of the

admissibility of expert testimony and the weight appropriately to be accorded such testimony by

a fact finder.” Ambrosini, 101 F.3d at 141; see also Lakie, 965 F. Supp. at 55 (ruling that the

defendant’s objections to expert testimony “confuse[] . . . the crucial distinction between the

31
admissibility of expert testimony and the weight such testimony should be afforded by the trier of

fact.”). The United States faults Bloch’s report: (1) for not identifying the species of tree from

which the limb came, citing to testimony by Kirk, an NPS arborist, that the species of tree is

relevant in risk assessment and tree-hazard identification, U.S.’s Mem. at 16 (citing Kirk Dep.,

14:5 to 14:18; 16:5 to 16:8; 21:13 to 21:21); (2) for resting heavily on the observation that “[i]f

this had been a live limb that fell, it would not have broken up in such small pieces,” without

backing that observation with citations to “arboreal texts” or any “citation to methodology,” id.

(quoting Bloch Report at 2); and (3) for “fail[ing] to provide any methodology or arboreal

science as to how a particular inspection would have identified this particular limb as

hazardous,” id. The Bloch Report’s silence as to these issues may represent “weak[nesses in the]

factual basis for his testimony,” Heller, 952 F. Supp. 2d at 140–41, but does not create “too great

an analytical gap between the data and the opinion proffered” to admit the testimony for

purposes of summary judgment, Gen. Elec. Co. v. Joiner, 552 U.S. 136, 146 (1997). Flaws that

do not reach that threshold are more appropriately addressed through motions in limine or,

ultimately, cross examination. See Daubert, 509 U.S. at 596.

Bloch’s failure to identify the species of tree asks for a judgment about “the credibility of

opposing” testimony—Bloch’s and Kirk’s—which courts cannot judge in determining the

reliability of expert testimony. See Ambrosini, 101 F.3d at 140. Finally, the United States’

criticism that Bloch does not use “any methodology” misses Bloch’s certification that his

conclusions “were developed, and this report prepared in conformity with . . . my expertise and

experience as a consulting arborist.” Bloch Report at 3; see also Pl.’s U.S. Opp’n at 13. This

signals that Bloch’s methodology was to “observe[] the relevant evidence” and “appl[y] [his]

specialized knowledge” to that evidence. Heller, 952 F. Supp. 2d at 141 (quoting Russell v.

32
Whirlpool Corp., 702 F.3d 450 457 (8th Cir. 2012)); see also Kumho Tire Co., 526 U.S. at 150

(recognizing that “personal experience” can form the basis for expert testimony). That is a

methodology “approved by courts in a variety of cases involving experts whose experience

forms the basis of their opinions.” Heller, 952 F. Supp. 2d at 141 (collecting cases); see also

Kumho Tire Co., 526 U.S. at 150 (“[T]he relevant reliability concerns may focus upon personal

knowledge or experience.”). Other courts have allowed such experienced-based testimony by

expert arborists. See Martin v. Norfolk So. Ry. Co., No. 16-cv-1191, 2018 WL 6840128, at *12

n.24 (Dec. 31, 2018) (concluding at summary judgment that “a registered arborist with many

decades of experience” would “likely” “be able to provide an expert opinion” admissible under

Daubert); see also United States v. Black Hills Power, Inc., 03-cv-5020, 2006 WL 6908315, at

*16 (denying a motion to strike the expert testimony of an arborist because those opinions were

based “at least in part” on a published article and because “[a]s an expert in the field, [the

arborist] can offer opinions based upon his experiences and observations.”). That Bloch’s report

relies on his experience, not “rampant speculation,” defeats the government’s arguments about

the report’s lack of citations to methodology. Heller, 952 F. Supp. 2d at 140; see also Joy v. Bell

Helicopter Textron, Inc., 999 F.2d 549, 568 (D.C. Cir. 1993) (“[A]dmission of expert testimony

constitutes an abuse of discretion only when that testimony qualifies as ‘rampant speculation’”).

2. Contributory Negligence

The substantive tort law of the District applies to the plaintiff’s FTCA action against the

United States, so the legal principles related to contributory negligence already laid out, supra in

Part III.A.3.b, apply to the United States’ contributory negligence defense. See 28 U.S.C.

§ 1346(b)(1) (“[U]nder circumstances where the United States, if a private person, would be

33
liable to the claimant in accordance with the law of the place where the act or omission

occurred.”).

The United States argues that it is entitled to summary judgment because the plaintiff was

contributorily negligent as a matter of law in disregarding “emergency management

instructions.” U.S.’s Mem. at 12. As support, the United States points out that “the District was

under a state of emergency in which the District’s Mayor and emergency management officials

had warned residents to remain indoors between noon and after midnight due to the risk of

falling trees, and when Plaintiff ventured out of her home to walk a tree-lined bridge at 3:15 p.m;

a tree limb fell on her in conditions described as ‘heavy rain and wind.’” Id. Yet, the plaintiff

has put these and related facts in dispute. As the United States acknowledges elsewhere, Mayor

Gray’s shelter-in-place warning was publicized as applying to the storm’s “peak.” See U.S.’s

Mem. at 11; see also Press Release (advising residents to “shelter in place during the peak of the

storm”). A press release did predict that the “peak” would begin “about noon Monday, [October

29],” but, as already discussed, the plaintiff offers evidence, in Downs’ expert report, that the

storm had not in fact reached its “peak” by 3:15 that afternoon, at least on the Connecticut

Avenue Bridge. See Downs Report at 3. Given this dispute, a trier of fact could question

whether the plaintiff indeed “fail[ed] to adhere to emergency-management instructions.” U.S.’s

Mem. at 12.

Moreover, the available facts do not lead to a single inference that the plaintiff’s decision

to go outside when the warnings were in effect was unreasonable. To start, as the plaintiff

emphasizes, citing the declaration of the witness Kimbuende, multiple other people were on the

Bridge with her, suggesting that ordinary care may not have required staying inside. See Pl’.s

U.S. Opp’n at 11 (citing Kimbuende Decl.). The plaintiff also observes that the State of

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Emergency was in effect from October 26 until November 10, 2012, see D.C. Emergency

Declaration at 3, which is well after the storm was over, see Pl.’s U.S. Opp’n at 10. That fact

strains nearly to the breaking point the United States’ argument that going outside during a state

of emergency is negligent.

The United States implies that any “failure to adhere to emergency-management

instructions constitutes a failure to employ reasonable care” as a matter of D.C. law, relying on a

single, almost sixty-year-old, non-binding, out-of-jurisdiction case, for the idea that ordinary care

requires, as a matter of law, a person to heed all emergency warnings. See U.S.’s Mem. at 11.

That case, Smith v. City of Kinston, 105 S.E. 2d 648 (N.C. 1958), merely indicates that “it may

be fairly inferred that” a resident of the area where a hurricane hit “knew of [a] hurricane and of

the devastation wrought by it.” Id. at 653. The United States also likens this case to Krombein v.

Gali Service Industries, Inc., 317 F. Supp. 2d 14 (D.D.C. 2004), which granted summary

judgment on a contributory negligence defense when a plaintiff walked across a floor, despite

one or two wet floor signs. Id. at 19. Krombein did not establish a per se rule that failure to

adhere to a warning is negligent; instead, summary judgment was granted there because the

plaintiff had not brought “to light any specific facts that create a genuine disputed issue between

the parties.” Id. Here, with facts in dispute, whether plaintiff’s decision to go outside despite the

warnings was unreasonable is a question for the trier of fact.

IV. CONCLUSION

For the foregoing reasons, the motions for summary judgment by the District and the

United States are DENIED. The parties are directed to confer and submit, by September 13,

2019, three proposed dates for trial of the plaintiff’s claims.

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An order consistent with this Memorandum Opinion will be entered contemporaneously.

Date: September 9, 2019

________________________
BERYL A. HOWELL
Chief Judge

36