Sigmund Timberg, 91, a Washington lawyer who worked for New Deal agencies and later focused in his private practice on international antitrust and intellectual property issues, died of pneumonia Feb. 12 at Suburban Hospital.

He lived in the District for nearly 70 years before moving six months ago to the Hebrew Home of Greater Washington.

Mr. Timberg was counsel on civil liberties and civil rights cases and for a court challenge that ended in a 1960 ruling that the D.H. Lawrence novel "Lady Chatterly's Lover" was not obscene and could be sent through the mail.

He taught at Georgetown and Columbia universities, lectured at other universities internationally and published more than 120 law articles.

He represented the United States at international conferences, served on law advisory committees and was a consultant to the Senate Patents Subcommittee, the United Nations Patent Study and the Organization of American States.

Mr. Timberg was born in Antwerp, Belgium, and raised in New York. He was a graduate of Columbia University, where he received a masters' degree in philosophy and a law degree.

He began his Washington career in 1933 as an attorney with the Agriculture Department's Soil Conservation Service and later worked for the Temporary National Economic Committee of Congress, the Securities and Exchange Commission and the antitrust division of the Justice Department.

During World War II, he was assigned to the Board of Economic Warfare, where he headed the property relations and industrial organization division during planning for the economic restructuring of post-war Europe. He was a member of the Mission for Economic Affairs in London and assisted in the occupation administration in Germany.

Mr. Timberg was a delegate to the Anglo-American Telecommunications Conference in Bermuda and the Geneva Copyright Conference. He was secretary of the United Nations' Committee on Restrictive Business Practices, the first institution to develop antitrust law on an international basis.

He went into private practice in the mid-1950s.

He was active in civic affairs in the Cleveland Park neighborhood of Northwest Washington and was a member of the Cleveland Park Historical Society and the neighborhood civic association. He was a member of the American and International Law Bar associations, American Society of International Law and American Law Institute.

He was a member of Friends of Forest Haven, the Cosmos, Torch and Washington Philosophy clubs, Adas Israel Congregation in Washington and the board of the Journal of Metaphysics.

His wife of 60 years, Eleanor Timberg, died last year.

Survivors include four children, Thomas Timberg of Jakarta, Bernard Timberg of Charlotte, N.C., and Rosamund Timberg and Richard Timberg, both of Washington; and four grandchildren.