In 1968, respondents (Pasadena, California high school students and their parents) brought a purported class action against various school officials seeking injunctive relief from allegedly unconstitutional segregation of the public schools in Pasadena. Ultimately, in 1970 the U.S. District Court ordered them to submit a plan for desegregating the Pasadena schools. The defendants did not appeal, and submitted the Pasadena Plan, which was approved by the District Court. In 1974, however, petitioner school officials filed a motion with the District Court seeking to modify the 1970 order. The District Court denied it. Petitioners appealed to the Court of Appeals. A divided panel of that court affirmed the District Court. Because the case seemed to present issues of importance regarding the extent of a District Court's authority in imposing a plan designed to achieve a unitary school system, the Supreme Court granted certiorari. It was held that, having adopted the Pasadena Plan in 1970 as establishing a racially neutral system of student assignment in the school system, the District Court exceeded its authority in enforcing its order so as to require annual readjustment of attendance zones so that there would not be a majority of any minority in any Pasadena public school. (Author/JM)