He began his practice as an associate with a major Inland Empire insurance defense firm. In 1990 he became a partner in the firm of Stanfield & Warner. During this time, Mr. Tierney’s practice was mainly dedicated to insurance defense, public entity and police civil liability for the County of San Bernardino. In 1996, Mr. Tierney’s firm merged with a leading Orange County defense firm and he became managing partner of their Inland Empire office. In 2000 he decided to change sides and began representing plaintiffs’ after spending over 16 years representing defendants in personal injury cases.