She has a "dissenting collar," which she explained to Couric "looks fitting for dissents."
She likely wore it for her dissent in the Supreme Court's Hobby Lobby decision, in which she said the court had "ventured into a minefield."
Ginsburg told Couric that the male justices who wrote the Hobby Lobby decision have a "blind spot" for women's issues.
She also has a collar for when she writes the majority opinion, which was a gift from her law clerks.
Watch the full interview, Ginsburg shows off her collar collection at the very beginning:
H/t Irin Cameron