Emmet Thornton was born and raised in New York. He joined the United States Air Force and served four years as a translator of the Northern Dialect of Vietnamese. Following discharge and two years teaching English in Tokyo, Japan he attended law school at McGeorge School of Law of the University of the Pacific in Sacramento, California where he was an honor student.
After graduation, he practiced as a trial lawyer for 36 years in San Francisco and Los Angeles. He is now retired and lives in Arizona with his wife, Monica Thornton, who is also an attorney.