Carl McGowan, 76, who steered a middle ground between sharply differing judicial philosophies while serving as a judge of the U.S. Court of Appeals for the District of Columbia, died of cancer yesterday at his home in Washington.

Judge McGowan, who was considered a moderating influence on what during the 1960s and 1970s was a deeply divided court, served 18 years before he assumed senior status and a reduced workload in 1981. He continued to serve as a senior judge until his death.

From January 1980 until May 1981, Judge McGowan was chief judge of the appeals court. Because of its location in the nation's capital and its jurisdiction over various federal agencies and programs, the panel is often considered second in importance only to the Supreme Court.

Lawyers and fellow judges who knew Judge McGowan described him as a man of powerful and persuasive intellect who often played the role of peacemaker among the feuding liberal and conservative factions on the court. He was said to have been a man of gentle demeanor whose written opinions reflected an attention to clarity and common sense.

He had a reputation for balancing individual and state interests in such a way that it was impossible to label him either liberal or conservative. His pragmatism made it equally difficult for lawyers practicing before him to predict how he might rule in a given case.

In a 1980 decision he articulated standards for determining the admissibility of a defendant's prior convictions at a criminal trial that were widely adopted elsewhere. He supported Supreme Court rules forbidding the use of illegally obtained evidence but at the same time urged law enforcement agencies to adopt internal procedures and sanctions that would make such rules unnecessary.

In a 1977 Freedom of Information Act lawsuit involving a background briefing by Henry A. Kissinger when Kissinger was head of the National Security Council, Judge McGowan delivered what was thought to have been the first judicial definition of a background briefing.

It is a procedure, said Judge McGowan, "designed to permit dissemination of information to the public, while simultaneously avoiding the risks associated with the direct quotation of high-ranking government personnel or official attribution of sensitive statements to government sources identified by name."

Judge McGowan was born in Hymera, Ind., and he grew up in Paris, Ill. He graduated from Dartmouth College and received a law degree from Columbia University law school.

From 1936 until 1939, he practiced law in New York City with what is now the law firm of Debevoise & Plimpton. He then joined the faculty at Northwestern University law school. He served in the Navy in Washington during World War II, and near the end of the war he was special assistant to the under secretary of the Navy.

Later he was associate general counsel for the Office of War Mobilization and Reconversion, then practiced law in Washington with the firm of Douglas, Proctor, MacIntyre & Gates.

In 1948 Judge McGowan returned to Illinois to rejoin the faculty at Northwestern law school. He was an assistant to Illinois' Democratic Gov. Adlai Stevenson from 1948 to 1952, and he was a campaign organizer in Stevenson's unsuccessful 1952 race for the presidency against Dwight D. Eisenhower.

After that election, Judge McGowan practiced law in Chicago while continuing to teach at Northwestern.

As a teacher he often complained that too many lawyers wrote poorly, and he observed once in an article in the Journal of the American Bar Association that too many of his colleagues used a brand of legal jargon that amounted to little more than "bushels of words, inexpertly put together."

Judge McGowan was appointed to the U.S. Court of Appeals in 1963 by President John F. Kennedy.

Responding to a contratulatory letter from Stevenson, Judge McGowan said of the appointment, "I am sure that you -- more than anyone else -- have always known that this is how I hoped to end up in the law and the public service."

Survivors include his wife, Josephine Perry McGowan of Washington; three daughters, Mary McGowan Davis of New York City, Rebecca McGowan of Ann Arbor, Mich., and Hope P. McGowan of Denver; one son, John H. McGowan of San Antonio, and three grandchildren.