California enacted its Global Warming Solutions Act (AB32) in 2006.

Since then, an entire network of interacting, mutually-reinforcing legislation  has evolved in the state,  historic in how the different measures support one another. A solar roof mandate (one million by 2020)  augments  an electric vehicle mandate (also one million in 2020), while both bolster  a 2020 mandate for all residential properties to be “net zero energy.”

The sectoral policies in AB32 are driving much of the emissions reduction today, while the state ramps up its carbon cap-and-trade market, which has so far operated six emissions credit auctions.  In 2010,  a challenge to AB32 appeared, and it was defeated by a wide margin by California voters.  Today, California is refining the elements