Josephine K. Mason


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San Francisco

Josephine is an attorney in Hanson Bridgett's Appellate Practice Group, where she focuses on appeals and writs in the state and federal courts. Her practice also includes drafting dispositive motions such as SLAPP, summary judgment, and post-trial motions, and partnering with trial counsel on litigation strategy.

Before joining Hanson Bridgett, Josephine served as law clerk to the Honorable James L. Dennis on the U.S. Court of Appeals for the Fifth Circuit. She began her career as an appellate attorney at the national appellate litigation boutique Horvitz & Levy LLP, based in Southern California.

Josephine’s appellate practice is complemented by her experience litigating complex and high-stakes business, commercial, securities, and environmental matters. Josephine also maintains an active pro bono practice, including handling appellate matters of public interest and drafting amicus curiae briefs in the state and federal courts.

Representative Work

Punitive Damages: As post-trial counsel, obtained a conditional remittitur reducing a $2.1 million punitive damage award to one third of the original award

Insurance: Obtained summary judgment in federal court in favor of the insured, ruling that the defendant had a duty to defend in the underlying class action 

Constitutional Law: Represented group of behavioral science and economics scholars as amici curiae in appeal addressing interplay between free speech and equal protection rights. Masterpiece Cakeshop, Ltd., v. Colorado Civil Rights Commission, No. 16-111 (U.S. Supreme Court)

Healthcare: Represented nonprofit organization as amicus curiae in support of the Director of the California Department of Public Health, in appeal involving challenge to California’s determination of death laws. Fonseca v. Smith, No. 17-17153 (9th Cir.)

Government: Represented municipal organizations as amici curiae in appeal addressing contours of antitrust and municipal immunity doctrines. AmeriCare MedServices, Inc. v. City of Anaheim, et al., No. 17-55565 (9th Cir.)

Anti-SLAPP, First Amendment: Secured favorable settlement and dismissal of complaint in full following filing of client’s opening brief on appeal. Wag Hotels, Inc. v. Puglisi, No. A146927 (Cal. Ct. App. 2015-2017)

Copyright: Assisted with drafting appellate brief in matter involving novel application of the copyright misuse doctrine. Omega S.A. v. Costco Wholesale Corp., 776 F.3d 692 (9th Cir. 2015)

Construction/real estate: Assisted with drafting appellate brief in real estate/construction matter, which settled following filing of client’s appellate brief. Pierre v. Cox, Nos. A132771, A131738, A1311342 (Cal. Ct. App. 2011-2012)

Pro Bono: Represented diverse group of amici curiae in right to education appeal in support of students seeking equal access to educational opportunity. Reed v. California, 208 Cal. App. 4th 322 (2012)

Pro Bono: Obtained reversal of order dismissing civil action on behalf of client asserting Truth in Lending Act violations. Matza v. Countrywide Home Loans, Inc., 433 F. App’x 591 (9th Cir. May 18, 2011)

Securities: Successfully represented directors, officers, companies, and investment funds in variety of securities and derivative actions

Consumer Class Action: Defeated class certification in consumer class action against national retailer, in litigation presenting an existential threat to the company (N.D. Cal. 2015-2017)

RICO: Obtained dismissal with prejudice of third-party complaint in complex federal RICO action with hundreds of millions at stake. Paskenta Band of Nomlaki Indians v. Crosby, No. 2:15-cv-00538-MCE-CMK, 2016 WL 3854237 (E.D. Cal. July 15, 2016)

Environmental: Served on litigation team in large-scale environmental case through historic, record-breaking settlement. In re Deepwater Horizon, MDL No. 2179, Nos. 10-3059 & 11-0516 (E.D. La. 2010-2015)

Environmental: Served on litigation team in large-scale environmental case from trial, post-trial briefing, through record-breaking settlement. N.J. Dep’t Envtl. Prot. v. ExxonMobil Corp., Nos. UNN-L3026-04 & UNN-L-1650-05 (N.J. Sup. Ct. Law Div. 2014-2015)

Each case is different. Prior results are no guarantee of future success.


"Arbitration Clauses, What's in Yours?" co-author, Appellate Insight Blog (April 2018)

"Must One Contest a Tentative Ruling?," Appellate Insight Blog (February 2018)

"Masterpiece Cakeshop': Drawing Lines to Ensure Tolerance Runs in All Directions," co-author, The Recorder (December 2017)

"Peremptory Challenge Denied? Take a Writ," Appellate Insight Blog (November 2017)

"MCLE: SLAPP Update," co-author, California Lawyer (December 2012)

"Why we need a federal anti-SLAPP law," co-author, Daily Journal (June 2012)

"The Wide-Ranging Applications of California Anti-SLAPP Law," co-author, Law360: Expert Analysis (February 2012)

"The Standing Doctrine's Dirty Little Secret," co-author, 107 Nw. U. L. Rev. 169 (2012)

"Uncertainty looms over anti-SLAPP issues," co-author, Daily Journal (December 2011)

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Professional Affiliations

Executive Committee of the Bar Association of San Francisco's Appellate Law Section

Queen’s Bench Amicus Committee, Co-Chair

U.C. Hastings Law Journal Alumni Board, Member

Judicial Clerkships

Law Clerk to the Honorable James L. Dennis, U.S. Court of Appeals for the Fifth Circuit (2012-2014)

Judicial Intern to the Honorable Edward Chen, U.S. District Court for the Northern District of California

Academic Distinction

Senior Articles Editor, Hastings Law Journal

Moot Court Board, Member

Order of the Coif


J.D., magna cum laude, University of California, Hastings College of the Law (2011)

B.A., summa cum laude, University of California, Berkeley (2008)

Admissions And Courts



San Francisco

415-995-5099 Direct Phone
415-995-3565 Fax

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