Justice Sonia Sotomayor recently declared historical amicus briefs to be “the most important” form of amicus briefing for the current bench. Yet no study has yet attempted to empirically track the devel-opment and influence of history-based amicus briefing. This article begins to correct this gap in our understanding, starting first by defin-ing the historians’ amicus brief subgenre of history-based briefing and analyzing its characteristics and influence with the Court as a complete population. The data reveals that historians’ briefs have received note-worthy judicial attention, with significantly higher overall citation rates than comparable forms of amicus briefing, including in numerous 5-4 cases. Historians’ briefs have repeatedly proven their use as both afacilitator of liberal coalition majorities and a tool of liberal dissents.They also provide historians with some means of securing their histor-ical conclusions against the “historiographic ventriloquism” ofmanipulative judicial citation.
