A lockable shield assembly for a syringe is described. The lockable shield assembly includes a moveable sleeve adapted to slide longitudinally along a body of the syringe from a retracted position where the needle of the syringe is exposed to an extended position wherein the moveable sleeve covers the needle. The assembly further includes a saddle member for attachment to the body of the syringe with the saddle member including a resilient tongue biased outwardly from the saddle member, wherein the resilient tongue engages with an abutment region located on the inner surface of the moveable sleeve to prevent retraction of the moveable sleeve when it has been moved to the extended position.