Allen Anderson Dobey, 70, a retired special assistant to the U.S. Attorney General and a former trial section chief in the Justice Department's antitrust division, died Saturday at Northern Virginia Doctors Hospital of a respiratory infection. He lived in Arlington.

A 35-year veteran of the Justice Department, Mr. Dobey was trial section chief in the antitrust division from 1966 to 1972. He retired in 1973 as special assistant to the U.S. Attorney General.

In 1961, he was honored by the Career Antitrust Lawyers Association as being "chiefly responsible" for a government suit preventing the merger of two steel firms, Bethehem Steel and the Youngstown Sheet and Tube Corp.

He also received a sustained superior performance award from the Justice Department in 1955 for his handling of the Eastman Kodak Co. film processing monopoly case.

Mr. Dobey was in Salisbury, N.C. He graduated from Catawba College in Salisbury and earned a law degree with honors from Yale University's law school in 1932.

He worked for a New York law firm before moving to the Washington area in about 1937.

During World War II, Mr. Dobey was a lieutenant in the Naval Reserve here.

Survivors include his wife, the former Martha Lindsly, of Arlington; two sons, Allen B., of Midwest City, Okla., and Robert B., of Arlington; a daughter, Mary Carol Coleman of Sheboygan, Wisc.; two sisters, Mrs. Philip F. Busby of Fort Lauderdale, Fla., and Mrs. John A. Hamilton of Summit, N.Y., and three grandchildren.