Robert W. Barker, 69, a prominent Washington lawyer and president of the Washington Temple of the Church of Jesus Christ of Latter-day Saints who had been active in professional and civic groups, died Dec. 31 at the Scripps Hospital in Encinitas, Calif., after a heart attack.

A resident of Kensington, he was vacationing in California when he was stricken.

Mr. Barker had served as law committee chairman for both Reagan presidential inaugurations and as general counsel and law committee chairman for the two Nixon presidential inaugurations.

He was a senior partner in the Washington law firm of Wilkinson, Barker, Knauer & Quinn, where he became an authority in Indian and communications law. He had been a counsel of Maurice H. Stans, former secretary of commerce and fund raiser for Nixon, during the mid-1970s. He also had been a vice president and general counsel of the Bonneville International Corp.

Mr. Barker had long been active in the D.C. Bar Association. During the 1960s, he had served as chairman of its standing committee on legislation and chairman of the U.S. Court of Claims committee. From 1966 to 1972, he was deputy chairman of its Indian law committee. He also had been a deputy chairman of the Indian law committee of the Federal Bar Association, a member of the Federal Communications Bar Association and was a fellow of the American College of Trial Lawyers.

Long active in the Mormon Church, he had been president of the Washington Temple since October 1985. Before that, he had served from 1967 to 1975, and again from 1977 to 1979, as regional representative of the Council of the Twelve Apostles. From 1957 to 1967, he was a member of the church's Washington Stake presidency. He also had been a counselor in the Washington Stake presidency and a bishop of the local congregation.

He had served on the executive board of the National Capital Area Council of the Boy Scouts of America.

Mr. Barker was a native of Ogden, Utah, and a 1941 honors graduate of the University of Utah, where he earned his degree in history and political science. In 1947, he graduated from Georgetown University law school where he earned the Lucey Medal, awarded to the graduating student with the highest academic standing. During World War II, he had served with the Army in the Mediterranean and European theaters, earning three Bronze Star medals and attaining the rank of major in the field artillery.

About 1950, he began practicing law here. From 1951 to 1953, he was administrative assistant to Sen. Wallace F. Bennett (R-Utah). Since 1953, he had engaged in the private practice of law. He was a founder of Wilkinson, Barker, Knauer & Quinn.

Survivors include his wife, the former Amy Thomas, of Kensington; a daughter, Amy Wilson of Cabin John, Md.; five sons, Robert W. Jr., of Kensington, Jeffrey C., of Ridgeland, S.C., Philip D., of Encinitas, Brian T., of Irvine, Calif., and Paul Thomas Barker of Silver Spring; three brothers, James B., of Coronado, Calif., Reese D., of Orinda, Calif., and Richard D., of Potomac; two sisters, Maude-Marian Bevan and Edith Harris, both of Salt Lake City, and 10 grandchildren.