concurring in the majority opinion.
While I concur in the judgment of the majority, I write separately because I find problematic the fact that the majority has considered the harmless error defense where it has not been properly raised by the respondent.
I agree with the majority that the state may introduce statements considered hearsay as evidence of a defendant’s culpability only where (1) the statements fall within a firmly rooted exception or (2) the statements contain particularized guarantees of trustworthiness such that adversarial testing would be expected to add little, if anything. See Ohio v. Roberts, 448 U.S. 56, 66, 100 S.Ct. 2531, 65 L.Ed.2d 597 (1980). Similarly, I do not dispute that the Supreme Court’s Confrontation Clause jurisprudence dictates that, as a matter of clearly established law, an unavailable co-defendant’s statements regarding the culpability of the defendant introduced by the prosecution to establish the defendant’s guilt neither fall with a firmly rooted hearsay exception nor bear any indicia of reliability. See Lilly v. Virginia, 527 U.S. 116, 119 S.Ct. 1887, 144 L.Ed.2d 117 (1999); Gray v. Maryland, 523 U.S. 185, 118 S.Ct. 1151, 140 L.Ed.2d 294 (1998); Williamson v. United States, 512 U.S. 594, 114 S.Ct. 2431, 129 L.Ed.2d 476 (1994); Idaho v. Wright, 497 U.S. 805, 110 S.Ct. 3139, 111 L.Ed.2d 638 (1990); Cruz v. New York, 481 U.S. 186, 107 S.Ct. 1714, 95 L.Ed.2d 162 (1987); Lee v. Illinois, 476 U.S. 530, 106 S.Ct. 2056, 90 L.Ed.2d 514 (1986); Bruton v. United States, 391 U.S. 123, 88 S.Ct. 1620, 20 L.Ed.2d 476 (1968).
While the district court correctly concluded that the inclusion of Erwin Mallory’s confession violated Calvert’s Sixth Amendment rights, that court also erred by considering the respondent’s harmless error argument. The majority opinion propagates that error by considering the harmless error argument here on the merits.1 While a petitioner has the responsibility of ensuring that all claims in support of a petition for writ of habeas corpus are *836timely raised, so too does the warden bear the responsibility of ensuring all defenses, including harmless error, are timely raised. See Hitchcock v. Dugger, 481 U.S. 393, 399, 107 S.Ct. 1821, 95 L.Ed.2d 347 (1987) (“Respondent has made no attempt to argue that this error was harmless ... [i]n the absence of such a showing our cases hold that the exclusion of mitigating evidence of the sort at issue here renders the death sentence invalid.”); United States v. Vallejo, 237 F.3d 1008, 1026 (9th Cir.2001) (“The Government does not argue that this error was harmless and thus waives that argument.”); Holland v. McGinnis, 963 F.2d 1044, 1057 (7th Cir.1992) (“Since Illinois did not argue harmless error in either of its briefs, it submitted [it] in a Rule 28© filing shortly after argument. The state’s belated attempt to inject [the harmless error defense] at oral argument is both disturbing and unavailing.”). See also Liebman & Hertz, Federal Habeas Corpus Practice and Procedure § 32.2a (3d ed. 1998) (“Like other defenses to habeas corpus relief, the ‘harmless error’ obstacle does not arise unless the state asserts it; the state’s failure to do so in a timely and unequivocal fashion waives the defense.”) Indeed, for evident reasons, “[procedural rules apply to the government as well as to defendants.” Wilson v. O’Leary, 895 F.2d 378, 384 (7th Cir.1990). Just as a defendant may not “save” claims for strategic purposes, the state may not place the harmless error defense in an arsenal for safekeeping in the event that its substantive constitutional arguments fail. See Yohn v. Love, 887 F.Supp. 773, 792 (E.D.Pa.1996), aff'd in part, rev’d in part, 76 F.3d 508 (3d Cir.1996), quoting Granberry v. Greer, 481 U.S. 129, 132, 107 S.Ct. 1671, 95 L.Ed.2d 119 (1987) (finding that the state must raise harmless error as an initial matter, such that it is prohibited from “seeking a favorable ruling on the merits while holding the defense in reserve for use after a finding of constitutional error.”). See also Liebman & Hertz, § 32.2a. Both parties must present their cards at the outset; as matter of fundamental fairness and judicial economy, hidden hands should not be encouraged.
Here, in its Return of Writ, the respondent failed to raise the harmless error defense.2 In a single footnote, without any recitation of legal standards or legal citations, the respondent mentioned that the “admission of [Mallory’s statement] ... if error at all, was harmless error in light of the other evidence admitted against Calvert.” In the same footnote, the respondent recited three mostly unpersuasive facts that the prosecution presented at trial.3 This footnote, without any further analysis, does not amount to an assertion of harmless error for the purposes of waiver. Indeed, it is generally held that an argument is not raised where it is simply noted in a footnote absent any recitation of legal standards or legal authority. See Nat’l Foreign Trade Council v. Natsios, 181 F.3d 38, 61 (1st Cir.1999) (“We have repeatedly held that arguments raised in a footnote or in a perfunctory manner are waived.”); Norton v. Sam’s Club, 145 F.3d *837114, 117 (2d Cir.1998) (“[W]e have held that an argument made only in a footnote [is] inadequately raised for appellate review”); John Wyeth & Bro. Ltd. v. CIGNA Intern. Corp., 119 F.3d 1070, 1076 (3d Cir.1997) (explaining that “arguments raised in passing (such as, in a footnote), but not squarely argued, are considered waived”); U.S. Dept, of Navy v. Fed. Labor Relations Auth., 975 F.2d 348, 352 (7th Cir.1992) (“arguments raised in passing in a footnote are waived.”) This conclusion is logical, given that a footnote merely supplements an existing argument; it is not, by definition, used to present a new argument or idea. See Webster’s Third New International Dictionary for the English Language Unabridged at 885 (Philip Bab-cock Gove, ed.1993) (defining a footnote as “a note of reference, explanation, or comment placed below” and “an utterance or action that is subordinated or added to a larger statement or event”). While the respondent presumably would not expect a court to consider on the merits a defendant’s footnotes containing simplistic legal conclusions, so too must he expect that similarly stated arguments by the respondent will likewise be considered waived.
It is worth noting that some federal appellate courts have held that even where the state waives the harmless error defense, a reviewing court has limited discretion to nonetheless conduct harmless error review. See United States v. Giovannetti 928 F.2d 225, 227 (7th Cir.1991) (holding that a court can determine if it possesses the requisite discretion to consider harmless error by considering “the length and complexity of the record, whether harmlessness of the error or errors is certain or debatable, and whether the reversal will result in protracted, costly, and ultimately futile proceedings in the district court”); Horsley v. Alabama, 45 F.3d 1486, 1492 n. 10 (11th Cir.1995); United States v. Langston, 970 F.2d 692, 704 n. 9 (10th Cir.1992); Lufkins v. Leapley, 965 F.2d 1477, 1481 (8th Cir.1992). These decisions are, of course, merely persuasive authority and are not binding on this Court. However, even if this panel were to subscribe to this analysis, we would be forced to conclude that we are without the discretion to consider harmless error, as the error here is not, as required by Giovannetti plainly harmless. This defense was thus improperly considered by the district court and the majority opinion.
The respondent does not argue here that under the Giovannetti fine of cases, this court may exercise its discretion to conduct harmless error review.4 Instead, respondent reiterates the finding of the district court that prior to the Supreme Court’s decision in Lilly, “respondent’s primary argument was that Mallory’s statement was admitted under a firmly rooted exception to the hearsay rule. The significance of a harmless error argument did not manifest itself until the decision in Lilly.” This reasoning is wholly inappo-site. As an initial matter, that Lilly was not yet decided at the time respondent was putting together his brief is entirely irrelevant. The decision in Lilly was based upon a firmly established line of Supreme Court precedent; the Lilly court was clear in stating that the Court’s holding was simply a logical extension of the Court’s prior Confrontation Clause decisions. See Lilly at 134, 119 S.Ct. 1887 (“Today we merely reaffirm [Bruton, Cruz, and Gray ] and make explicit what was heretofore implicit: A statement that falls into the cate*838gory summarized in Lee — a confession by an accomplice which incriminates a criminal defendant — does not come within a firmly rooted hearsay exception.”) Furthermore, if the respondent expected that his chief argument — that, notwithstanding the holdings in Gray, Cruz, Lee, and Bru-ton, a co-defendant’s out of court statement used as evidence of a defendant’s guilt falls with in a firmly rooted hearsay exception — would prevail, he certainly is entitled to that approach. However, once this argument fails, respondent may not then call on the district court to entertain additional defenses. This attempt to strategically reserve defenses until they are necessary is precisely why courts have held that the state must assert harmless error at the outset or waive the defense entirely. See e.g., Granberry v. Greer, 481 U.S. 129, 132, 107 S.Ct. 1671, 95 L.Ed.2d 119 (1987). This Court should not, as a matter of policy, encourage poorly planned lawyering or improper strategy, nor should this Court to do the respondent’s job for him by raising harmless error where he has failed to do so appropriately. I find it troubling that the respondent has essentially asked this Court to do as much, particularly given the broad sweep of responsibilities that is accorded to the respondent in these proceedings and the liberty interests at stake.
For the aforementioned reasons, I concur in the judgment only of the majority opinion.
. The majority states that the waiver of harmless error argument is of no consequence because the error here is not harmless. That argument is backwards: the majority essentially concludes that because the defense has no merit, then the procedural health of the defense need not be examined, when in fact, particularly in the habeas context, a court is charged with determining the procedural integrity of a claim before making an inquiry as to its merits.
. Notably, the respondent also did not raise harmless error before the Guernsey County Court of Appeals and, by extension, the Ohio Supreme Court, upon direct appeal.
. These were: (1) the fact that Calvert had Bennett’s blood on his clothes and fingernails; (2) that Calvert uttered to Mallory in the presence of a cab driver, "we showed him;” and (3) Calvert told Crystal Harris that he hit an African-American man with a hatchet and did not know if he killed him. Calvert has consistently stated that he was present in Bennett's apartment when he was killed and was covered in Bennett’s blood when he was arrested. Crystal Harris also testified that she did not think that Calvert was serious when he said that he hit someone with a hatchet; at any rate, Bennett was not African-American.
. The respondent also argues that its waiver of harmless error issue should not be considered by this Court, as it is outside the scope of the District Court’s certificate of appealability. This argument clearly lacks merit, as the propriety of considering harmless error is certainly part and parcel of Calvert’s Confrontation Clause claim.