Two cases decided over the last three months have added California[1] and Massachusetts[2] to the list of minority states that hold brand name manufacturers of drugs (“Brand Manufacturers”) liable under state “failure to warn” laws when sued by patients that exclusively used a generic version of the Brand Manufacturer’s drug. These cases follow the US Supreme Court decision in PLIVA, Inc. v. Mensing, 131 S. Ct. 2567 (2011) (“PLIVA”), which held that generic drug manufacturers cannot be held liable for failure to update the safety label of a drug or biologic in violation of state “failure to warn” tort law since regulations from the U.S. Food and Drug Administration (“FDA”) prohibit generic manufacturers from unilaterally updating a generic drug’s label . Following PLIVA, the FDA proposed a rule entitled, “Supplemental Applications Proposing Labeling Changes for Approved Drugs and Biological Products” (“Proposed Rule”) meant to allow generic drug or biologic manufacturers (“Generic Manufacturers”), under certain circumstances, to update safety labels without the requirement that the label match the label of the Brand Manufacturer. The Proposed Rule also would have required Generic Manufacturers in certain circumstances to collect post-market safety information. However, after twice delaying publication of a final rule, the FDA withdrew its Proposed Rule last year. Now that the Proposed Rule has been withdrawn, manufacturers holding New Drug Applications or Biological License Applications (collectively herein, “NDAs”) for the drugs or biologics they manufacture are faced with increased uncertainty with regard to the application of state “failure-to-warn” duties and liabilities, especially in light of the recent decisions by the California and Massachusetts supreme courts.