Ruth Borenstein is engaged in a complex litigation practice at both the trial and appellate levels in courts throughout the country. Her practice currently emphasizes transportation law, issues related to federal jurisdiction and preemption, class actions, and other complex civil litigation. Her cases have included defending class actions challenging the rates and service practices of a global package transportation company, bringing suit on behalf of cargo carriers to enjoin enforcement of state laws regulating carriers' services, filing amicus briefs on behalf of the cargo carrier industry, as well as a variety of commercial litigation matters.

Ms. Borenstein has served on the Board of Directors of the Bar Association of San Francisco, which has honored her as a Pro Bono Attorney of the Year. She was the primary author of the Bar Association of San Francisco's Model Domestic Partners Health Benefits Policy. Ms. Borenstein is a member of the California Bar, and is admitted to practice in numerous federal courts, including the United States Supreme Court.

Ms. Borenstein joined Morrison & Foerster in 1987.