Government interference with sterile syringe programs is thwarting HIV prevention efforts in California. State laws and local enforcement are preventing drug users from obtaining the sterile syringes they need to protect themselves from HIV. This 61-page report documents police stopping, arresting, and harassing participants in needle exchange programs established by some California counties under state law. Even where needle exchange programs are legal, police remain authorized to arrest program participants under an antiquated law prohibiting the possession of “drug paraphernalia.” Over a quarter of new AIDS cases in the United States can be traced to infected syringes. Sharing syringes is also a major risk factor in the spread of hepatitis B and C. California is home to nearly one eighth of reported AIDS cases in the United States. The Human Rights Watch report recommends legalization of needle exchange programs and nonprescription pharmacy sales of syringes. It also calls on police departments to cease stops and seizures of participants in clean needle programs, a practice courts have recently prohibited in Connecticut, Massachusetts and New York.