While there's no record of a judge citing Islamic law for precedent, Oklahoma voters passed a proposition banning that from happening. It wasn't a squeaker, either; early results show it passing by a 40 point margin.
Republican Representative Rex Duncan said the law "will constitute a pre-emptive strike against Shariah law coming to Oklahoma." Duncan talked about the proposition on Sean Hannity's Fox News in June:
The law also banned judges referring to international law, as well as requiring all state business to be conducted in English.
What do you think of the law? Would you like to see a law like this in California, or would you oppose a similar proposition?