 Under the theory that federal law passed pursuant to Constitutional authority overrules conflicting state laws, federal authorities still claim the authority to seize, arrest, and prosecute for possession and sales of these substances, even in states where they are legal under state law.The first wave was the legalization by 27 states of laetrile in the late 1970s.This drug was used as a treatment for cancer, but scientific studies both before and after this legislative trend found it to be ineffective.