Don't know if it's a law or not. I do know that here in Illinois, all gas has 10% in it now. 2 years ago that wasn't the case. BP/Amoco's gas didn't use to have ethanol in it. Now it does. Habeeb used to brag that his gas didn't have alky in it. I use it for the 93 ocatane and haven't had a problem since it went over to the alky blend.