I had a tonic-clonic seizure and the neurologist told me not to drive for 6 months. It is the law?

Varies by state. Every state is different in terms of how long the restriction lasts, as well as if the physician is obliged to report the seizure to the dmv. If you have an accident while driving during the period when you are supposed to not be driving, the penalties are severe. For your sake and the sake of others on the road, don't risk it!