Garrison then completed a judicial clerkship in Philadelphia, Pennsylvania and became a practicing attorney. She moved to Marietta in 1990, joining the law firm of McCauley, Webster & Emrick, where she became a partner in 1993. Three years later, she opened a private law practice, concentrating on family mediation. She ran the Washington County Visitation Mediation Project for seven years, providing free mediation to parents working out their custody and visitation conflicts. She has served on the boards of the domestic violence shelter EVE and the Washington County Mental Health & Alcohol Addiction Board, and as Commissioner on the Marietta Civil Service Board.