This Article uses the absence of Montesquieu from American Supreme Court decisions to highlight some problems with American separation of powers law.  Recently, the Court has embraced a neoformalist approach, allegedly justified by the Constitution’s “original meaning.”  Yet the Court never cites to Montesquieu, despite his influence, and rarely engages with early republic history.  This Article uses scholarship on Founding era practice to show that 18^th century understandings of separation of powers were not formalist.  It thus uses Montesquieu to recover an alternative, more pragmatic and historically accurate understanding of separation of powers, in place of the Court’s growing fetishism.