The Court's methodological innovations in this analysis were two-fold. First, Justice Kennedy explained that rather than placing absolute priority upon the formal articulation of a rule in England, one must examine "why common-law courts lacked . . . power" to issue the writ in certain contexts (p. 19). In responding to this question, he insisted that, in some instances, prudential concerns dictated the outcome of decisions at common law denying issuance of the writ.
Second, and even more importantly, Justice Kennedy maintained that the historical indeterminacy of the answer to the question of whether alien prisoners detained abroad were permitted access to the writ at common law did not prevent the Court from concluding that such individuals might be entitled to the writ. As he explained, "Both [the Government's and the petitioners'] arguments are premised . . . upon the assumption that the historical record is complete and that the common law, if properly understood, yields a definite answer to the questions before us. There are reasons to doubt both assumptions. . . . We decline, therefore, to infer too much, one way or another, from the lack of historical evidence on point" (p. 22). Justice Scalia, critiquing the majority's deployment of history in his dissent, instead argued that a lack of definitive evidence should lead to the assumption that no right of access to the writ existed (pp. 7-8).
The majority's treatment of the status of the common law at the time of the Founding may mean that it is finally acknowledging the relevance to constitutional interpretation of something other than what John Reid has aptly named "forensic legal history." As Justice Kennedy wrote, citing to Paul Halliday and G.E. White's The Suspension Clause (pp. 12-15), "Recent scholarship points to the inherent shortcomings in the historical record." These shortcomings are inevitable when history is treated in all its complexity. At the same time, as I argued in Towards a Common Law Originalism, historical indeterminacy should not simply cause the Court to give up in despair; instead, it can valuably investigate the historical record to ascertain the reasons and arguments for the particular positions that this record might support before arriving at its own conclusions. By considering the pragmatic considerations that led English courts to deny the writ in various instances, Justice Kennedy did just that.