Katherine Drew Hallgarten, 72, a Washington lawyer for more than 35 years with extensive experience in government and private practice, died Saturday at the Washington Home. She had undergone surgery for brain tumors.

Mrs. Hallgarten was a specialist in communications law, including space communications. She was a former chairman of the communications section of the Inter-American Bar Association. She also had chaired a discussion on the future of space law at a meeting of the International Astronautical Federation.

At the time of her death, she was associated with the law firm of Arent, Fox, Kintner, Plotkin & Kahn.

A native of San Francisco, Mrs. Hallgarten graduated from Stanford University and earned a law degree at the Univeristy of California in Berkeley in 1938. She did legal aid work and worked in the wartime Office of Censorship in San Francisco before moving to Washington in 1944.

She began her career here as a lawyer in the Office of the Coordinator of Inter-American Affairs in the State Department. At the time she left State in 1953, she was counsel for Latin America in the Office of the Legal Advisor.

From 1953 to 1959, she was in private practice here and spent a year studying international communications law in Cologne, Germany. From 1959 to 1964, she was attorney and assistant director of the Presidential Commission on International Rules of Judicial Procedure. She then returned to private practice here.

In 1974, she was retained by Honduras to write a telecommunications law for that country, which has been enacted.

Mrs. Hallgarten, who lived in Washington, was a member of the American D.C. and Federal bar associations as well as of numerous other professional organizations.

Her husband, Dr. George W. F. Hallgarten, died in 1975.

Survivors include a sister, Viva Drew Adamson of Washington.