A restraint system includes a wrist restraint system and an ankle restraint system that allow the limbs of a detainee to be restrained. The lockable wrist restraint system includes a waist belt and wrist restraints that are rotatably mounted to the waist belt. The wrist restraints can be positioned anywhere around the waist belt. The lockable ankle restraint system includes a strap and two buckles that form the strap into two loops. Each loop is used to restrain a leg of the detainee. A lockable buckle includes a housing that creates a tortuous path that traps a strap to which the buckle is mounted and prevents the strap from being adjusted or removed from the detainee.