There isn’t a federal standard, but there is a common state-level standard in the US with class 1, 2, and 3. Class 1 cuts out at 20 mph and must be assist-only. Class 2 also cuts out at 20 mph, but may also have a throttle that works without peddling. Class 3 cuts out at 28 mph and may or may not have a throttle. Technically there are laws around not taking class 3 e-bikes in some spots, but I have found with mine as long as I ride it like a class 1 (15-20 mph max), no one bothers me. However, none of them require a license or insurance.