By law, how many methods of applying brakes must all automobiles have?

All automobiles are required by law to have two separate methods of applying brakes. This dual-brake system is designed to enhance safety, ensuring that if one brake method fails, the other can still be utilized to stop the vehicle effectively. This requirement helps prevent accidents caused by brake failure, providing drivers with an additional layer of reliability when operating their vehicles. The two methods typically consist of the primary braking system (which operates normally during driving) and a secondary system, often relying on different components or mechanisms, which serves as a backup.