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Practice Areas

Consumer Protection Litigation, Mass Tort Litigation, Employment Litigation, Complex Business Litigation


For over two decades, Mark J. Tamblyn has dedicated his career to handling complex litigation, on both the plaintiff and defense sides, securing meaningful relief for his clients by resolving high-stakes disputes through verdict or settlement.


Mark began his legal career prosecuting consumer and antitrust class action cases. He expanded his breadth through defense of large companies concerning alleged wage and hour violations and alleged discriminatory practices in one of the largest labor and employment law firms in the country.


Mark developed early a national reputation for an aggressive yet sensible consensus-building approach toward the handling of complex litigation on behalf of his clients. He has organized and supervised to successful conclusion scores of class actions. He has been asked to lecture on the class action practice and its evolving legal developments, and has been voted by his peers as a Super Lawyers Rising Star in the class action and mass tort practice areas. For public service, Mark has also served as a Deputy Attorney General in the California Department of Justice, Office of the Attorney General, representing large California state agencies and government officials primarily in complex, multi-party actions. 

Representative Actions

  • In re: Midwestern Pet Foods Marketing, Sales Practices, and Product Liability Litigation, Case No.: 3:21-cv-00007 (S.D. Ind.). Individually appointed interim Co-Lead Counsel in consolidated class action on behalf of a proposed class of consumers of pet food products, allegedly contaminated with a toxic mold known as Aflatoxin, as well as the Salmonella bacteria.


  • Parry v. Farmers Insurance Exchange, et al., Case No. BC683856 (L.A. Sup.). Lead capacity in achieving resolution of class certified insurance agent action claims, resulting in $75 million settlement. 



  • United Food & Commercial Workers Union and Employers Midwest Pension Fund, et al. v. Allianz Global Investors U.S. LLC, et al., Case No. 20-cv-9587 (KPF) (S.D.N.Y.). Lead capacity in successful recovery of millions in pension fund losses as a result of alleged misrepresentation of hedging against major market crashes, when the defendants allegedly failed to execute on those hedges.


  • In re Pet Food Products Liability Litigation, MDL - 07-2867 (D.N.J.). Lead capacity in national and cross-border settlement involving more than 100 class action lawsuits concerning pet foods that were found to contain toxic ingredients imported from China. Settlement of $24 million.


  • Glasscock v. Serco, Inc., Case No. 1:20-cv-00092 (JFA) (E.D. Va.). Lead capacity in successfully resolved ERISA class action concerning administration and management of employee retirement plans.


  • Illinois Biometric Information Privacy Litigation (BIPA) (multiple jurisdictions). Acted in lead capacity in multiple BIPA class action cases involving the wrongful collection of biometric data, including fingerprints, from employees and consumers. 


  • In re America Online Spin-Off Accounts Litigation, MDL-1581 (C.D. Cal.). Lead capacity in class actions involving allegations of creation of unauthorized online accounts (so-called spin-off accounts) for certain subscribers, assessment of charges for accounts; and preventing subscribers from obtaining refunds for unauthorized charges


  • In re OSB Antitrust Litigation, Case No. 06-826 (E.D. Pa.). Leadership responsibilities on behalf of a class of purchasers of oriented strand board (OSB), a structural panel wood product used throughout the United States in residential construction for sheathing and flooring. 


  • Champion Pet Foods Litigation (multiple jurisdictions). Pet food class action litigation in federal jurisdictions throughout the country, involving misrepresentations over the quality and content of pet food products.


  • Zeiger v. Wellpet LLC, Case No. 3:17-CV-04056-WHO (N.D. Cal.). Obtained class certification and successful resolution of action alleging sales of dog food products allegedly contaminated with arsenic and lead, and the chemical Bisphenol A. 


  • In re Brazilian Blowout Litigation, GIB LLC Cases, JCCP No. 4657 and C.D. Cal. In Re Brazilian Blowout Litigation, Case No. CV 10-08452 JFW (MANx). Settlement of over $4.5 million in class action involving alleged misrepresentations of hair-straightening product.