People infected with HIV who persist in exposing others to infection through negligent, reckless, or criminal activity create a legal and ethical dilemma for public officials. Protection of the public health requires balancing the rights of infected people with the expectations of society. When reasonable efforts fail to obtain the voluntary cooperation of infected individuals, Colorado law permits health officers to restrict their behaviour. Since 1986, at least 20 people who were aware of their infection are known to have exposed others to HIV in Colorado Springs, Colorado. Restrictive measures have been initiated in 14 cases to date. Presented here is an overview of Colorado law, selected case studies, and a summary of its strengths and shortcomings.