Scooters worldwide meet highly varied regulatory climates, since the classifications vary from country to country. For example, France, Italy and Spain allow drivers with an automobile driver's license to operate motorcycles up to 125 cc. In order to ride larger motorcycles in those countries a rider would need an additional motorcycle license. In most other E.U. countries, as well as in Japan, one can only ride motorcycles up to 50 cc with an automobile driver’s license.

Most jurisdictions have no legal definition for scooters, and instead classify scooters with engines smaller than 50 cc as mopeds, and subject them to lower safety restrictions and licensing fees. Scooters above 50 cc are usually legally considered motorcycles, although some jurisdictions have an in-between definition for motorized bike for scooters and motorcycles between 50 and 150 cc. In the E.U. all two-wheeled motor vehicles above 50 cc are classified as motorcycles.

In the United States the term "scooter" is rarely stipulated as a motor vehicle classification — which usually is based on characteristics such as number of wheels, sitting configuration, engine size, power, and maximum speed. In the U.S. and Europe, scooters fall into either motorcycle or moped category depending on their engine characteristics and sitting configuration, and each subject to laws for their respective category.

The United States Department of Transportation defines a scooter as having a platform for the operator's feet or has integrated footrests, and has a step-through architecture.

The term scooter and motor scooter lead to much confusion. For all legal purposes, the NHTSA recommends using the term motorcycle for all of these vehicles. The government itself is also a little confused as they are excluding the term motor scooter from the legal definition but proceed to give detail instructions on how to import a small motor scooter. See the NHTSA article

In Victoria and New South Wales in Australia, scooters are classified as motorcycles and a rider would need the appropriate motorcycle permit in order to ride one