California's ground breaking CO2 cap and trade program may be in jeopardy, after a Superior Court in San Francisco County issued an injunction against the California Air Resources Board (CARB) prohibiting the agency from any further rule making under its "Climate Change Scoping Plan". The challenge to CARB's cap and trade proposal was brought by environmental justice advocates, who believe that cap and trade would impose disproportionate air quality impacts on low income and minority communities. These advocates believe that a carbon tax is preferable to cap and trade since it would incentivize emission reductions at all facilities equally. The court ruled that CARB did not sufficiently evaluate alternatives to cap and trade as required under the California Environmental Quality Act (a state version of NEPA).

It is not clear whether CARB's related rules, most significantly its renewable portfolio standard, will also be delayed by the ruling.