Abstract: A combination mechanical and electronic lock system for use in cuffs and various other locking applications is disclosed. In the preferred embodiment, the lock is configured to receive a matching key that transmits a code that disengages the electronic lock from the mechanical lock so that the mechanical lock can be manually opened by the user. When implemented in a handcuff, for example, the mechanical lock includes a single lock mechanism and a double lock mechanism; and at least one electronic lock configured to selectively unlock at least a portion of the mechanical lock upon receipt of the proper digital code from the cuff key. The power needed to operate the electronic lock, preferably a solenoid or other actuator, is received directly or indirectly from the cuff key so that the cuff need not possess a battery.