On September 15, 2023, California filed a lawsuit against the major oil companies, presenting claims under a variety of theories, including public nuisance and false advertising.  This lawsuit is similar to ones filed by other state attorneys-general (e.g., Minnesota, Delaware, Rhode Island) and to lawsuits filed by a number of municipalities and local governments across the United States, including a number of California cities and counties (e.g., San Francisco, Oakland, San Mateo County, Marin County).  In truth, this is merely the latest lawsuit filed in an effort stretching back to 2017 to hold the oil majors (and similar fossil fuel companies) liable for the effects of global climate change, primarily under a theory of public nuisance. 

This array of cases, while initially delayed in procedural battles (e.g., a question concerning the scope of appellate review of removal issues went all the way to the Supreme Court), have gained additional traction recently, as many of the cases are now proceeding apace in various state courts.  It is possible that the State of California now chose to join this chorus of lawsuits due to a perception that the legal terrain is now more favorable following the initial groundwork laid by the first lawsuits filed.  

But the significance of California joining this legal crusade should not be underestimated.  The State of California is an immense and powerful entity, and one which can claim substantial damages--more than other plaintiffs--based upon the theory of damages articulated by these cases, which focuses on the consequences of climate change and the impact on communities (e.g., drought, wildfire, flooding).  Further, the fact that California has now also filed a lawsuit may encourage other states and local governments to do so, exerting additional pressure on the oil majors.