dissenting.
I
Section 20(a) of the Longshoremen’s and Harbor Workers’ Compensation Act (LHWCA), 33 U. S. C. § 920(a), provides that “it shall be presumed, in the absence of substantial evidence to the contrary . . . [t]hat [a] claim [for compensation] comes within the provisions of this chapter.” The central issue before us is whether this provision requires the employer in a compensation hearing to offer “substantial evidence” refuting the existence of a causal relationship between a compensation claimant’s injury and his employment. The question has been fully briefed and argued, but the Court does not address it. For me, however, the answer is clear and controls the proper disposition of this case.
By its terms, and quite in contrast to the practice in judicial proceedings, § 20(a) requires the employer to take the initial steps to disprove his liability. This preliminary shifting of the burden to the employer exemplifies the “humanitarian nature of the Act,” O’Keeffe v. Smith Associates, 380 U. S. 359, 362 (1965) (per curiam), and the “strong legislative policy favoring awards in arguable cases;” Wheatley v. Adler, 132 U. S. App. D. C. 177, 183, 407 F. 2d 307, 313 (1968) (en banc). Section 20(a) is clearly broad enough to encompass the question of causation. “The statutory presumption applies as much to the nexus between an employee’s malady and his employment activities as it does to any other aspect of a claim. ” In re District of Columbia Workmen’s Compensation Act, 180 U. S. App. D. C. 216, 223, 554 F. 2d 1075, 1082 (1976). To defeat a claim for compensation, the employer must rebut the presumption of compensability by offering substantial evidence that the claim is not one “arising out of and in the course of employment.” 33 U. S. C. §§902(2), 903; see Marra Bros., Inc. v. Cardillo, 154 F. 2d 357 (CA3 1946). Only after the employer offers such substantial evi*618dence does the presumption fall “out of the case.” Del Vecchio v. Bowers, 296 U. S. 280, 286 (1935).
The statutory presumption thus defines the basic agenda for the hearing before the Office of Workers’ Compensation Programs (OWCP), and the factfinding required before the OWCP may deny a compensation claim. In this case, there is no serious dispute that respondent Riley suffered some disabling injury.1 See Riley v. U. S. Industries/Federal Sheet Metal, Inc., 200 U. S. App. D. C. 402, 406, n. 3, 627 F. 2d 455, 459, n. 3 (1980). Riley has an arthritic neck condition, and “the pain [he] suffered . . . was due to an exacerbation of his arthritic neck condition.” Id., at 405, 627 F. 2d, at 458. Given the existence of this condition, and the statutory presumption, the relevant inquiry was whether the employer had shown that the condition was not sufficiently work-related to render the employer accountable.2 No such finding was ever entered. Rather, the Administrative Law Judge and the Benefits Review Board focused exclusively on the testimony of Riley and his co-worker that something happened to Riley while lifting duct work on November 19,1975, causing an immediate pain in his neck. The Administrative *619Law Judge concluded only that no such incident occurred; the Benefits Review Board affirmed that finding.
Had the Administrative Law Judge credited the testimony of Riley with respect to the November 19 incident, it would surely have strengthened Riley’s position that the exacerbation of his arthritic neck condition was work-related. But the finding that this incident did not occur hardly demonstrates that Riley’s disability did not arise out of and in the course of employment. An injury need not be traceable to a single event at work in order to be compensable. “Even if the asserted work-related incident had never occurred, the injuries suffered by the claimant might nevertheless have been ‘employment bred.’”3 Id., at 406, 627 F. 2d, at 459. *620Absent a finding excluding this possibility, compensation could not be denied. In addition, the failure of the Administrative Law Judge to focus on the broader issue of the injury’s work-relatedness suggests that he may have failed to conduct the proceedings with proper attentiveness to the basic issue in a case such as this: namely, had the claimant been disabled as a result of his employment? Because the agency did not make the crucial finding, the Court of Appeals quite properly remanded this case so that the necessary determination could be made.
HH hH
Rather than allow a remand so that the normal process of administrative adjudication might run its course, the Court discerns a dispositive procedural requirement within the Act. The Court places its emphasis on the language of § 20(a):
“In any proceeding for the enforcement of a claim for compensation under this Act it shall be presumed, in the absence of substantial evidence to the contrary . . . [t]hat the claim comes within the provisions of this Act.” (Emphasis added.)
Unremarkably, the Court reads this language as applying the presumption to the “claim for compensation.” But quite remarkably, and without any support in precedent or the language of the Act, the Court construes the words “claim for compensation” to mean some sort of legal document, or at least some stated theory, setting forth a prima facie case for compensation, upon which all further proceedings must be based, and to which the presumption may attach.
The Court appears to glean its understanding of the word “claim” from the meaning assigned to the term “claim for relief” by Rule 8(a) of the Federal Rules of Civil Procedure. The Court concedes, as it must, that this understanding of the word “claim” finds no direct authority in the LHWCA itself. The Act does require the employee to file a timely “claim” with the Deputy Commissioner. 33 U. S. C. *621§ 913(a). See ante, at 613. But it is clear that the referred-to “claim” is nothing more than a simple request for payment,4 carrying with it the implicit assertion of an entitlement to compensation. To the extent an allegation of “time, place, nature, and cause of injury” is statutorily required, it is only in connection with the notice to the employer referred to by § 12.5 33 U. S. C. §912.
Moreover, the Court’s reliance on a written pleading requirement is wholly out of step with the sensible informality with which the Act is administered.6 Under the present regime of administrative enforcement, issues are not narrowed through pleadings, but rather through a mixture of formal *622and informal prehearing procedures. 20 CFR §§702.311-702.317 (1981). The regulations governing the administration of the Act reflect the method chosen by the agency charged with administering the Act for addressing the practical problems of issue narrowing that inevitably arise in the course of administrative proceedings. In addition to the prehearing conference report, which sets, forth the issues for the hearing, the parties are required to submit a prehear-ing statement defining the issues to be considered. See §702.317. Nevertheless, the employee’s failure to raise a particular issue at the prehearing conference, or in his prehearing statement, does not preclude him from raising that issue at the formal hearing. See § 702.336(a). In addition, “[a]t any time prior to the filing of the compensation order. . . the administrative law judge may in his discretion” reopen the hearing to consider a new issue. § 702.336(b).7
Apparently the Court is of the view that its imported definition of “claim” is necessary to protect employers from being called into a compensation hearing without any warning of the basis upon which compensation is sought; on this argument, the employer would otherwise be forced to offer evidence refuting every conceivable basis upon which an employee’s claim might be grounded. I do not share the Court’s fear. The Act already contains sufficient accommodation to such legitimate employer concerns: in the form of a statutory notice requirement, in the practical manner in which the presumption of compensability has historically *623been applied, and in the good-sense application of agency regulations and case management principles by the administrative officials charged with the execution of this Act’s provisions. In sum, I am confident, as the Court apparently is not, that any legitimate claim of surprise by the employer in this or in any other case may be fairly considered within the framework of the governing regulations, and resolved in a manner that effectuates the humanitarian purposes of this Act. Rather than rely on some Active legal analysis to dispose of the case “as a matter of law,” by intertwining the problem of notice with the § 20(a) presumption, I would leave all such questions of proof and notice for the agency on remand, as did the Court of Appeals.
r — i k-H u-4
As Justice Douglas once had occasion to remind us, “[tjhe problems under this Act should rest mainly with the Courts of Appeals.” O’Keeffe v. Smith Associates, 380 U. S., at 371 (dubitante). The Court’s treatment of the relatively simple issues raised by the present case underscores the wisdom of that counsel of deference. The Court of Appeals concluded below that the relevant issues were never resolved by the Administrative Law Judge. I can hardly disagree. Therefore, I dissent.
It may be that the opinion for the Court of Appeals suffered from failing to distinguish between the use of the term “injury” in its ordinary meaning, and in its specialized meaning under the Act. See 33 U. S. C. § 902(2). But there is absolutely no basis for the suggestion in Part II of the Court’s opinion that the Court of Appeals thought it sufficient to ground a compensation claim on an “injury” that “arose in bed, not in the course of employment.” Ante, at 616. The suggestion is plainly wrong; virtually every aspect of the opinion for the Court of Appeals reaffirms that the issue before the Administrative Law Judge and the Benefits Review Board was whether there existed some causal connection between the claimant’s disability and his employment.
In practice, the two tests of “arising out of” and “in the course of” tend to merge into a single determination of work-relatedness. See 1A A. Larson, The Law of Workmen’s Compensation §§29.00-29.10, pp. 5-354— 5-357 (1979). The dissenting member of the Benefits Review Board Panel thus properly described “the real issue in this case” as “whether claimant’s injury is causally related to his employment.” 9 BRBS 936, 940 (1979).
It is surely plausible that there was a causal relation between the exacerbation of Riley’s arthritic neck condition and the overhead sheet metal duct work that he was engaged in until the night he awoke in bed in pain. But however logical this connection might be in some lay sense, it could hardly assure Riley of recovery. The term “substantial” is relative, and the quantum and type of evidence required of the employer correspond to the specificity of the claimaint’s evidence and allegations. The evidence necessary to overcome the presumption is least when the claim rests — as this one apparently did once the testimony respecting the November 19 accident was rejected — on little more than some arguable link between the disabling condition and the nature of the work.
There appears to be little in the abbreviated record before this Court directly supporting this broader theory of recovery. Although one physician testified that “[t]he man is certainly disabled from working,” App. 130, this statement was made in the course of questioning about the possible effects of the alleged November 19 incident. Another doctor, describing Riley’s condition shortly after he entered the hospital, noted: “[Mjost of his work is overhead type and involves quite a bit of hyperextention of the neck. That means that most of his work he will have to do with his neck bending upwards.” Id., at 158. That same doctor, however, referred repeatedly to Riley’s assertion that he felt pain as a result of bending or twisting his neck while lifting duct work in November 1975, and rendered his diagnosis on that basis. See id., at 162-169. Although Riley hardly proved his theory by this medical evidence, given the nature of the injury and the nature of his work, Riley clearly made the “initial demonstration of employment-connection [that] will give the presumption a foothold.” 1 A. Larson, supra, § 10.33, at 3-121 (1978).
This definition of “claim” comports with its accustomed meaning in the context of comparable compensation statutes. For example, “claim” is defined for purposes of the Federal Mine Safety and Health Act of 1977, 30 U. S. C. § 801 et seq. (1976 ed. and Supp. IV), as “a written assertion of entitlement to benefits under [the Act], submitted in a form and manner authorized by the provisions of this subchapter.” 20 CFR § 725.101(a)(16) (1981). See also 20 CFR § 10.5(a)(7) (1981) (Federal Employees’ Compensation Act, 5 U. S. C. § 8101 et seq.).
The Court’s reliance on the notice requirement of § 12 to suggest that the claim encompass some allegation of “time, place, and manner,” so that the Court can in turn conclude that the statutory presumption applies to what is alleged in the “claim,” is a patchwork job. The “claim” is something entirely apart from the § 12 notice. Indeed, § 12(d) employs the very distinction that the Court seeks to blur: “Failure to give such notice shall not bar any claim under this chapter” where the employer had actual notice, the Deputy Commissioner excuses such notice, or where no objection was raised to the failure “before the deputy commissioner at the first hearing of a claim for compensation . . . .” 33 U. S. C. § 912(d).
For example, the regulations provide that “[t]he order in which evidence and allegations shall be presented and the procedures at the hearings generally. . . shall be in the discretion of the administrative law judge and of such nature as to afford the parties a reasonable opportunity for a fair hearing.” 20 CFR § 702.338 (1981). That same regulation provides that “[i]f the adminstrative law judge believes that there is relevant and material evidence available which has not been presented at the hearing, he may ... at any time, prior to the filing of the compensation order, reopen the hearing for the receipt of such evidence.”
Although I do not profess expertise in the administration of the LHWCA, it does seem to me that this provision might have relevance in a case, such as the present one, where the administrative law judge intends to reject the claimaint’s principal theory of the case, but where a second theory should be more fully explored before the question of compensation is finally determined. Of course, I would leave questions regarding the application of this and all other regulations governing LHWCA proceedings for the Review Board to resolve on remand. See also 20 CFR § 702.336(a) (1981).