Al O'Brien grew up in Seattle.  He enlisted in the Marine Corps right out of high school, and took part in the first two major land battles of the Vietnam War in August and September of 1965.  After his discharge from active duty, Al was hired by the Seattle Police Department where he worked for twenty-nine years.  During his time with the police department, Al earned a Master's Degree in Public Administration from Seattle University.  The Chief of Police took Al off the street and put him in the policy writing unit where Al spent three years writing policy for the chief. 

Al was elected to the Mountlake Terrace City Council in 1991.  After five years on the Council, Al O'Brien was elected to the Washington State House of Representatives.  The Speaker of the House appointed Al chairman of the House Criminal Justice & Corrections Committee; a position that Al held for ten years.  Al served fourteen years in the legislature, retiring in 2011.

Al began teaching at Seattle University in 2008.  Al O'Brien teaches the graduate level course "Criminal Justice Legislation & Policy," with a focus on how criminal law is written.