Rodríguez v. Popular Democratic Party, 457 U.S. 1 (1982), was a case in which the Supreme Court of the United States heard on appeal from the Supreme Court of Puerto Rico whether Puerto Rico may by statute vest in a political party the power to fill an interim vacancy in the Puerto Rico Legislature. The Supreme Court of Puerto Rico held that such a procedure did not violate the United States Constitution, and the US Supreme Court upheld the decision of the Supreme Court of Puerto Rico. The case was of some interest to close followers of the Court as it featured the one and only return of former associate justice, Abe Fortas, now in private practice, at oral argument on behalf of the appellee.
A member of appellee Popular Democratic Party (hereafter "appellee") who was elected in the November, 1980, general election to the Puerto Rico House of Representatives from District 31, died in 1981. The Governor of Puerto Rico subsequently called for a "by-election" — open