Justin Starin was born in Kalispell and raised in Butte and Augusta, Montana. He graduated from college and law school at the University of Montana. Justin was admitted to the State Bar of Montana in 1999.
After working in Helena at the Montana Supreme Court, the District Court, and the Montana School Boards Association, Justin moved to Missoula and began private practice.
In 2009, Justin argued a case before the United State Court of Appeals for the Ninth Circuit, in which the Court held an insurance company must pay attorney fees if it denies a person the full benefit of the insurance policy.