- California
Rosanne Mah
Rosanne L. Mah represents consumers in complex class action litigation involving deceptive and misleading practices, false advertising, and defective products. She also represents survivors of childhood sexual abuse in Boy Scouts Sexual Abuse Litigation and in New Orleans Catholic Church Sexual Abuse Litigation.
Rosanne is integrally involved in client relations, including communicating with class members, through all stages of the litigation process, from intake to settlement.
Rosanne has over 15 years of experience in providing the highest level of legal representation to individuals and businesses in a wide variety of cases. Throughout her legal career she has specialized in consumer protection, defective products, cybersecurity, data privacy, and employment law at several law firms, as well as through her own practice. Rosanne attended the University of San Francisco, School of Law, during which she was a judicial extern with the Honorable Anne Bouliane of the San Francisco Superior Court. During law school, she advocated for tenants facing housing issues, including eviction and habitability problems.
She is a member of the California Bar and is admitted to practice before the United States Court of Appeals for the Ninth Circuit and the United States District Courts for the Northern, Central, Eastern, and Southern Districts of California.
Rosanne Mah has been absolutely understanding, responsive and professional. I couldn’t thank her enough.
- Scott A.
admissions−
awards+
Outstanding Volunteer in Public Service Certificate, 2010-2011, Debt Defense and Education Clinic for the Bar Association of San Francisco's Volunteer Legal Services Program
education+
- J.D., University of San Francisco School of Law, 2005
- B.A., University of California, Santa Cruz, 1995
Presentations & Articles+
Ethical Issues in Mass & Class Actions – Representation Challenges and Responsibilities
Legal Ethics Committee of the San Francisco Bar Association
September 11, 2025
Litigation Highlights
Vallin v. PNC Investments, LLC, et al.
Rosanne represents PNC current and former customers with brokerage accounts, advisory accounts, and retirement accounts who had cash deposits or balances in the PNC cash sweep program. Plaintiffs claim that PNC pays unreasonably low interest rates to customers in its cash sweep program while generating massive profits for themselves.
Biederman, et al. v. FCA US LLC, et al.
Rosanne represents current and former Ram truck owners and lessors with model years 2013 to 2018 Ram 2500 and Ram 3500 trucks equipped with a Cummins 6.7-Liter diesel engine. Plaintiffs allege that FCA US and Cummins together designed, manufactured, and sold 2013-2023 Ram 2500 and 3500 diesel trucks with undisclosed and unauthorized emission control devices that illegally bypass, render inoperative, or otherwise reduce the effectiveness of the vehicles' emission control system.
In re Midwestern Pet Foods Marketing, Sales Practices and Product Liability Litigation
Rosanne represented consumers alleging that Midwestern Pet Food sold dog food containing dangerous levels of Aflatoxin and Salmonella that was harmful to pets. Judge Matthew P. Brookman granted final approval of a nationwide class action settlement providing for a common fund of $6.3 million to compensate purchasers of the recalled pet food products for pet injury claims and consumer food purchaser claims.