Ronald D. Eastman, 70, a Washington lawyer and former general counsel to the Democratic National Committee, died Aug. 18 at the Angels Garden, an assisted living center in Rockville.

He died of Alzheimer’s disease, said his wife, Hope Eastman.

Mr. Eastman began his legal career in 1966 as a lawyer with the Federal Power Commission. He was a partner at the former Verner, Liipfert, Bernhard, McPherson and Hand; at Cadwalader, Wickersham & Taft; and at the former Swidler & Berlin law firm, where he retired because of illness in 1994.

Following the 1976 presidential election and until 1981, Mr. Eastman was general counsel to the Democratic panel. In that capacity, he won a 1981 U.S. Supreme Court ruling affirming the committee’s right to determine delegate selection procedures for Democratic national conventions.

That case involved Wisconsin’s open primary law, which allowed non-Democrats to vote in Democratic Party primaries. Mr. Eastman argued before the high court in 1980 that Wisconsin is powerless to “dictate to the Democratic Party how it selects its nominees.”

The Supreme Court of Wisconsin had ruled that delegates to the national convention were bound by the results of these primaries, which, it said, took precedence over the national party’s rule that only declared Democrats be allowed to vote in binding primaries.

Mr. Eastman successfully argued before the U.S. Supreme Court that the Wisconsin court decision impermissibly violated the First Amendment rights of the national party and its members.

Mr. Eastman also had been volunteer counsel to Sen. Edmund S. Muskie (D-Maine) in the 1972 presidential campaign and special counsel to President Jimmy Carter’s pre-nomination campaign.

Ronald David Eastman, who lived in Kensington, was born in San Antonio. He graduated from the University of Texas in 1963 and from Harvard Law School in 1966.

Survivors include his wife of 44 years, Hope Ehrlich Eastman of Kensington; two sons, Alexander Eastman of Dallas and Andrew Eastman of Philadelphia; and a brother.

— Bart Barnes