Nathaniel J. Ely, 66, a lawyer who helped with Navy management problems during and after World War II, and later helped in the development of Alaskan oil and gas fields, died Saturday of cancer of Georgetown University Hospital.

He had also served as a Montgomery County Tax Court judge and as chairman of the D.C. police trial board.

Mr. Ely lived in Bethesda and had another residence in Frenchtown, Md.

He was born in Baltimore, and attended public schools there. He later studied music at the Peabody Institute, and accounting and economics at Johns Hopkins University. In 1936 he received a law degree from the University of Baltimore. He also studied at the Industrial College of the Armed Forces.

A lawyer who specialized in administrative law, Mr. Ely was in private practice at the time of his death. His career combined athletics, government service, business and law.

He was a runner, and trained for the 1936 Olympics. Because the games were held in Munich and opened by Adolf Hitler, Mr. Ely, who was Jewish, did not participate, his family said.

In the late 1930s, he served as a director of the World Maccabee Organization, a group that organized the first Jewish Olympic Games in Tel Aviv.

In 1941, Mr. Ely, then a Naval reservist, was called to active duty. After Pearl Harbor, he was transferred to the Bureau of Ships. In addition to property acquisition, contract work and special projects, he acted as the Navy's representative to the ocean shipping section of the Army-Navy Munitions Board.

Mr. Ely also served as the Navy member of the National Planning Commission for Demobilization and Reconversion. He was released from active duty in May, 1946, but continued to serve in the Naval Reserve. He was recalled to active duty for special jobs, including a review of naval material manpower utilization, a merger of naval bureaus, a study of the administration of naval petroleum reserves and a review of regulations governing organizational conflicts of interest.

He retired from the military in 1970, but continued to act as a special adviser to the Navy Department on general procurement policy matters.

In the early 1950s, before exploration and development of the oil and gas fields (in which he participated) was well under way, Mr. Ely helped plan and organize a Native Trust Fund for the Tlingit Tribes of Southeastern Alaska and arranged for payments to the fund by oil and gas operators drilling off the Gulf of Alaska.

Over the years he served as an officer or a director of several companies, including Craig Instrument Company, Aerologiclal Research, Aspen Terrace, Inc., Aspen Hill Development Company, Fairhill Construction Company, Yakutat Development Company, Northern Development Company, Alaska-North American Investment Company and Unified Industries.

He was appointed judge of the Appeal Tax Court in Rockville in 1954, and served until 1964. He helped streamline court procedures and helped draft legislation establishing the Maryland State Tax Court.

Mr. Ely was also a U.S. representative to the International Center for the Settlement of Investment Disputes, a treaty organization operating within the World Bank and the International Bank for Reconstruction and Development. He served as a concilliator.

Mr. Ely also helped with fundraising for Loyola University of Los Angeles during the 1940s, and served as secretary of the Baltimore Recreation Commission, which helped establish a Baltimore City Recreation Department.

More recently, he worked with a committee to acquire for D.C. Children's Hospital a skin-grafting machine for the treatment of children's burns. He also worked as an adviser and counselor to the president of Georgetown University, helping with liaison with the administration and Congress on such projects as medical-dental aid, campus housing and the Georgetown University Hospital Concentrated Care Center.

He was a director of the D.C. Bar and chairman of its administrative law section.

He was also a member of the Woodmont Country Club, the Samuel Gompers Masonic Lodge, the Army-Navy Club, the Jewish War Veterans, the American Legion and the Retired Officers Association.

He is survived by his wife, Sylvia, of the home; his mother, Sarah Wertlieb, of Silver Spring; two sisters, Lilian Rattner, of Washington, and Jean Gordon, of Rockville; three daughters, Ilona Freedman, of Alexandria, Diana Epstein, of Potomac, and Robin A. Ely, of the home, and two grandchildren.