Removal of legal barriers to the operation of NEPs and other syringe access initiatives has been identified as an important part of a comprehensive approach to reducing HIV transmission among IDUs. Legal barriers include both "law on the books" and "law on the streets", i.e., the actual practices of law enforcement officers, which may or may not reflect relevant law. Changes in syringe and drug control policy can be ineffective in reducing such barriers if police continue to treat syringe possession as a crime or participation in NEP as evidence of criminal activity.