Removal of legal barriers to syringe access has been identified as an important part of a comprehensive approach to reducing HIV transmission among injecting drug users (IDUs). Legal barriers include both “law on the books” and “law on the streets,” i.e., the actual practices of law enforcement officers. 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 evidence of criminal activity. Despite the integral role of police officers in health policy implementation, little is known of their knowledge of, attitudes toward, and enforcement response to harm-minimisation schemes. We conducted qualitative interviews with 14 police officers in an urban police department following decriminalisation of syringe purchase and possession. Significant findings include: respondents were generally misinformed about the law legalising syringe purchase and possession; accurate knowledge of the law did not significantly change self-reported law enforcement behaviour; while anxious about accidental needle sticks and acquiring communicable diseases from IDUs, police officers were not trained or equipped to deal with this occupational risk; respondents were frustrated by systemic failures and structural barriers that perpetuate the cycle of substance abuse and crime, but blamed users for poor life choices. These data suggest a need for more extensive study of police attitudes and behaviours towards drug use and drug users. They also suggest changes in police training and management aimed at addressing concerns and misconceptions of the personnel, and ensuring that the legal harm reduction programs are not compromised by negative police interactions with IDUs.