Obviously you don't have a very good understanding of how our system works. The SCOTUS reviews and interpret laws to interpret them and rule on their constitutionality. It may strike down laws or rule on how they may be applied. it does not tell states that they must pass a law. With regards to seat belts and helmets, there is no question regarding interpretation and there is certainly no constitutional issue. If anything, a case might be brought that requiring helmets and seatbelts is unconstitutional but that would be a stretch,