WASHINGTON (AP) _ Oliver Gasch, a long-time federal judge who presided over the trial of Lyndon Johnson's top Senate aide and who later ruled that President Carter had violated the Constitution, died Friday.

Gasch died following heart surgery at Georgetown University Hospital. He was 93.

Active in Republican politics, Gasch was appointed a federal judge in 1965 by the Democratic President Johnson. Four years later he presided over the influence peddling trial of Senate Secretary Bobby Baker, who had been Johnson's top aide in the Senate. Baker was convicted and sentenced to one to three years in prison.

Gasch also presided over the government corruption trials of Rep. Charles C. Diggs Jr., D-Mich., and Rep. Daniel J. Flood, R-Pa., in the 1970s. In the case against Carter, he ruled that the president violated the Constitution in unilaterally terminating a mutual defense treaty between the United States and Taiwan. That decision was reversed by an appeals court.