The panel was composed of Judges Lynch (Clinton nominee), Torruella (Reagan), and Boudin (GHWB); the opinion was written by Judge Boudin, who served as Chief Judge for the First Circuit from 2001-08.
Interestingly, the panel holds that DOMA does have a rational basis ...
Under such a rational basis standard, the Gill plaintiffs cannot prevail. Consider only one of the several justifications for DOMA offered by Congress itself, namely, that broadening the definition of marriage will reduce tax revenues and increase social security payments. This is the converse of the very advantages that the Gill plaintiffs are seeking, and Congress could rationally have believed that DOMA would reduce costs, even if newer studies of the actual economic effects of DOMA suggest that it may in fact raise costs for the federal government.... but that a heightened standard instead applies, per the Moreno/City of Cleburne/Romer line of cases I've previously discussed:
Without relying on suspect classifications, Supreme Court equal protection decisions have both intensified scrutiny of purported justifications where minorities are subject to discrepant treatment and have limited the permissible justifications. And (as we later explain), in areas where state regulation has traditionally governed, the Court may require that the federal government interest in intervention be shown with special clarity.In a set of equal protection decisions, the Supreme Court has now several times struck down state or local enactments without invoking any suspect classification. In each, the protesting group was historically disadvantaged or unpopular, and the statutory justification seemed thin, unsupported or impermissible. It is these decisions--not classic rational basis review--that the Gill plaintiffs and the Justice Department most usefully invoke in their briefs (while seeking to absorb them into different and more rigid categorical rubrics)....
All three of the cited cases--Moreno, City of Cleburne and Romer--stressed the historic patterns of disadvantage suffered by the group adversely affected by the statute. As with the women, the poor and the mentally impaired, gays and lesbians have long been the subject of discrimination. Lawrence, 539 U.S. at 571. The Court has in these cases undertaken a more careful assessment of the justifications than the light scrutiny offered by conventional rational basis review.