Born in Los Angeles, California, Alarcón was a Staff Sergeant in the United States Army from 1943 to 1946, then received a Bachelor of Arts degree from University of Southern California in 1949 and a Bachelor of Laws from USC Gould School of Law in 1951.

He was an associate justice of the California Court of Appeal Second Appellate District from 1978 to 1979.

[1] On August 28, 1979, Alarcón was nominated by President Jimmy Carter to a new seat on the United States Court of Appeals for the Ninth Circuit created by 92 Stat.

He was confirmed by the United States Senate on October 31, 1979, and received his commission on November 2, 1979.

[1] He assumed senior status on November 21, 1992, and served until his death in Pacific Palisades, California, on January 28, 2015.