Arthur J. McLauglin, 76, a retired assistant U.S. attorney for the District of Columbia and a former chairman of the D.C. Mental Health Commission, died of respiratory arrest Saturday in a hospital in New Haven, Conn.

Mr. McLaughlin was a trail lawyer with the U.S. attorney's office for 28 years before retiring in 1963. He prosecuted some of the most publicized cases of the day.

These included the trial of Monte Durham, a housebreaker whose case led to a landmark appeliate court ruling that rewrote Washington's criminal insanity laws.

Under this precedent, District juries were required to acquit a defendant if they found that his crime was the product of a mental disease or defect.

Mr. McLauglin won the 1948 conviction of two young brothers, Lawrence and George Garner, for the murder of a D.C. taxi driver.

As they were led from the courtroom after their convictions George Garner tossed a note to Mr. McLaughlin. It said:

"Mc: You did a nice job. I have no hard feelings for you. Good luck in any job you might get. George A. Garner."

Both the Garner brothers went to the electric chair for their crime.

Mr. McLaughlin was chairman of the D.C. Mental Health Commission, the city agency that controlled civil committee procedures for six years until retiring a second time in 1969.

He was a native of New Haven, Conn., and a 1935 graduate of Georgetown University's law school. He served in the Coast Guard during World War II.

Mr. McLaughlin was a resident of New Haven at the time of his death.

His survivors include two sisters Mrs. Harry A. Conte and Mrs. Henry G. Guenther, both of New Haven.