Prior to her appointment to the bench, Justice Sepulveda served as a Deputy District Attorney in Contra Costa County for eleven years, handling all types of criminal cases and serving in various administrative positions including heading the Sexual Assault and Child Abuse Unit and the Juvenile Division. She graduated from Hastings College of the Law in 1977, having written for and served as a Note & Comment Editor on the Constitutional Law Quarterly. Justice Sepulveda graduated Summa Cum Laude from U.C. Berkeley in 1974, receiving her B.A. in Psychology.
Justice Sepulveda is a member of the California Judges Association and has been active in judicial education throughout her career on the bench. She has chaired or served on numerous planning committees for judicial conferences and has taught many times at the Judges' College, New Judge Orientation, the Continuing Judicial Studies Program and the Criminal and Family Law yearly institutes. She was a member of the Sentencing Committee for the Judicial Council, which was charged with revising the Rules of Court re: Determinate Sentencing in 1989. She served as a judicial representative on the statewide Restitution Committee. She has served on the statewide Trial Court Budget Commission (the T.C.B.C.), and on its Executive and Budget Evaluation and Appeals Committees, since 1995. She served as Chair of the Budget Evaluation and Appeals Committee and just prior to her elevation to the appellate bench was appointed by the Chief Justice as Vice-Chair of the T.C.B.C.