Is a habeas petition 'second or successive' when the factual predicate giving rise to the petitioner's claim occurs long after the petitioner filed his initial habeas petition?

Question Presented for Review Section 2254 habeas corpus proceedings exist for state prisoners to vindicate their federal constitutional rights. Through the enactment of the Antiterrorism and Effective Death Penalty Act (“AEDPA”), Congress sought to conserve judicial resources, reduce piecemeal litigation, and streamline federal habeas proceedings. As a result, it imposed heightened gateway requirements that petitioners must meet before filing a “second or successive” petition. 28 U.S.C. § 2244(b)(2). But those gatekeeping provisions apply only to petitions that are abusive, or would otherwise negatively implicate AEDPA’s purposes. As this Court and the Circuits have explained, (1) the term “second or successive” petition is a term of art that must be defined in reference to the historical abuse-of-the-writ doctrine, which bars only those claims that could have been (but were not) raised in the first petition; and (2) requiring petitioners to file unripe claims in their initial habeas petition wastes judicial resources, increases piecemeal litigation, and does not contribute meaningfully to the finality of state convictions. Therefore, as this Court explained in Panetti v. Quarterman, petitions raising newly ripened claims are not “second or successive,” and are not subject to the heightened gatekeeping provisions of § 2244(b)(2). Mr. Hill was convicted and sentenced to death in 1986 for aggravated murder, based on “scientific” testimony that Mr. Hill (and only Mr. Hill) could have caused a “bitemark” on the victim’s penis. That testimony constituted the only direct evidence i that Mr. Hill was an active participant in the crime, rather than a passive observer. Decades after Mr. Hill filed his initial habeas petition challenging that conviction, the American Board of Forensic Odontology (“ABFO”) invalidated the bitemark science used to convict Mr. Hill of aggravated murder. No longer are forensic odontologists permitted to opine that any particular individual created a particular bitemark. Not only that, Mr. Hill presented expert testimony that, applying the current (and correct) scientific standards, the injury to the victim was not even a human bitemark. Mr. Hill promptly raised a federal constitutional challenge based on the invalidation of the bitemark testimony in state court. Following the Ohio state courts’ rejections of this challenge, Mr. Hill filed a habeas petition in the district court. The district court determined that Mr. Hill’s petition was “second or successive,” and transferred his case to the Sixth Circuit for authorization pursuant to § 2244(b)(2). The Sixth Circuit panel agreed with Mr. Hill that his petition was not “second or successive,” but the full court vacated the panel’s decision and, sitting en banc, determined that Mr. Hill’s petition was “second or successive.” It returned Mr. Hill’s case to the panel for a determination pursuant to § 2244(b)(2). In so holding, the Sixth Circuit strayed from the precedent of this Court and the Circuits. Mr. Hill now raises the following question for this Court’s review: Is a habeas petition “second or successive” when the factual predicate giving rise to the petitioner’s claim occurs long after the petitioner filed his initial habeas petition? ii