Sophia B. Castillo

Sophia B. Castillo: Attorney with Keller and Heckman LLP

Biography

Sophia (Sophie) Castillo counsels domestic and international importers, distributors, national brands, private labels, institutional suppliers, family-owned food processing businesses, and retail grocers on compliance, litigation, and risk avoidance surrounding California’s Proposition 65, as well as other state and national laws related to chemicals and toxics. She advises clients involved in numerous industries across the entire supply chain, including food and beverage, cosmetics and personal care, dietary supplements, apparel, cookware, consumer products, and retail.

Sophie has an in-depth understanding of how exposure analysis provides the basis for California’s Proposition 65 and continues to stay abreast of the evolving regulation. She helps clients create compliant warning and labeling statements, conducts audits, and, if the need arises, will litigate and defend clients in Proposition 65 cases, including assisting with bounty-hunter claims.

In addition to Proposition 65, Sophie counsels clients on other state laws, including California’s regulations related to PFAS and other emerging contaminants in products such as food packaging, cookware, and cosmetics. She also has experience working with chemical disclosure laws in the cosmetics and personal care products space. In her litigation practice, Sophie defends scientific and environmental law and toxic tort cases in litigation and regulatory proceedings and litigates complex multi-party Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and contaminated property cases. Sophie also defends toxic tort matters involving chemicals in foods, beverages, consumer products, and pharmaceuticals.

Due to her vast knowledge of the legal landscape within these industries, Sophie is often invited to speak at industry conferences and author thought-leadership articles.

Prior to joining Keller and Heckman, Sophie was a litigation and Proposition 65 partner at a California-based law firm.

Awards

•The Best Lawyers in America : Environmental Law; Litigation - Environmental, 2024 - 2026
•Super Lawyers, San Francisco, Environmental; Environmental Litigation, 2024 - 2026
•JD Supra Readers’ Choice Awards, Food & Beverage, Top Author, 2021 - 2023, 2025
•Attorney Intel, Top 50 Attorney of San Francisco, 2023
•U.C. Hastings Pro Bono Attorney Honor Roll, U.C. Hastings Center for Gender and Refugee Studies, 2012
•Hastings Law Journal, Articles Editor, 2004 - 2005
•U.C. Hastings Moot Court Team, Roger Traynor Appellate Moot Court Competition, Second Place - Best Oral Argument, 2004

Insights & In the News

December 2025 Bounty Hunter Plaintiff Claims

01.23.2026
Publication

November 2025 Bounty Hunter Plaintiff Claims

12.19.2025
Publication

October 2025 Bounty Hunter Plaintiff Claims

11.25.2025
Publication

Best Law Firms Features Keller and Heckman in 2026 Edition

Press Release
11.06.2025

See more ›

Areas of Practice (10)

  • California's Proposition 65
  • Environmental and Toxic Tort Litigation
  • Food and Drug
  • Food Litigation
  • Litigation
  • Product Safety
  • Sustainability and Product Stewardship
  • Chemicals and Plastics
  • Consumer Products and Retail
  • Food & Life Sciences

Education & Credentials

University Attended:
University of California, Los Angeles, B.A., cum laude, 2002
Law School Attended:
University of California, Hastings College of the Law, J.D., 2005
Year of First Admission:
2005
Admission:
2005, California; U.S. Court of Federal Claims; U.S. Court of Appeals for the Ninth Circuit; U.S. District Court, Central District of California; U.S. District Court, Northern District of California; U.S. District Court, Eastern District of California; U.S. District Court, Southern District of California
Memberships:

Memberships

•Food and Drug Law Institute (FDLI), 2025 Austern Writing Awards Committee
•Prop. 65 Clearinghouse, Advisory Board Member
•ProVisors Network Member
•National Charity League, Inc.

Birth Information:
Tallahassee, Florida, February 11, 1980
Reported Cases:
Representative Matters: Advised companies throughout the supply chain (European and U.S. manufacturers, importers, distributors, national brands, private label brands, family-owned food processing businesses, and retail stores) on warning mandates of California's Proposition 65 for chemicals in products, with focus on food and beverage, apparel, cooking appliance, and grocery industries; Defended, litigated, and settled Proposition 65 plaintiff claims and advised clients on associated indemnity obligations throughout the supply chain, including various industry-wide Proposition 65 matters; Provided compliance advice to U.S. and European companies regarding California chemical and recycling regulations, including PFAS/AB 1200, California's toxics in packaging regulations, and grocery recycling regulations; Represented client in multi-year natural resource damages (NRDA) regulatory process; Litigated contaminated groundwater/soil cases pursuant to CERCLA and state law; Litigated toxic tort matter related to alleged cancer-causing chemicals in pharmaceutical product; Frequent presenter on Proposition 65 and related issues for trade groups, including the Specialty Foods Association, the Association of Food Industries, and the California Grocers Association
ISLN:
918570701

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