Abstract: A syringe assembly includes a syringe barrel (12) having a proximal end and a distal end, a needle hub (20) supporting the needle and coupled to the distal end of the syringe barrel (12). A moveable shield (36) is included for sliding from a first position where the needle is exposed a first length, a second position where the needle is exposed a second length less than said first length, and a third position covering a distal end of the needle. A locking mechanism (48, 86) is included to retain the shield in the second position while enabling the shield to slide to the third position, and to lock the shield in the third position to prevent re-use of the syringe.