The 74-year-old Breyer has taken up the seat in the academy – one of the five academies of the Institut de France – formerly held by the last heir to the Austro-Hungarian empire, Otto Habsburg, who died in July 2011.
Breyer, who has spent 18 years as one of nine justices on the top US court, on Monday accepted the honor in a Paris ceremony attended by his wife Joanna, their daughter Chloe and two of his grandchildren.
"We must be better informed about the law and legal methods practiced in other countries," Breyer said in an induction speech delivered in fluent French, noting how more and more legal cases are transcending national borders.
The justice – who was named to the Supreme Court by former US president Bill Clinton – also emphasized the importance of the rule of law and the need to "step up the fight against tyranny, in all its forms."
There are 12 foreign members of the Academy of Moral and Political Sciences, including retired pope Benedict XVI, Britain's Prince Charles, Spain's King Juan Carlos and Peruvian former UN secretary general Javier Perez de Cuellar.
The body – which focuses on the discussion of philosophy, law and political economy – has about 50 French members.