The least intrusive coercive public health measure is the involuntary testing of populations at risk for communicable disease. The most common example is testing for tuberculosis in high- risk populations. Involuntary testing has three benefits. First, it allows public health officials to learn the prevalence of a disease in the community. This is difficult to accomplish with voluntary testing because of the statistical problems associated with self-selected data sets. Second, it identifies infected individuals who may benefit from treatment. Third, it identifies individuals who may need to be restricted to protect the public health.

Involuntary testing for communicable diseases is legally different from testing for personal behavior such as drug use or the propensity to steal from an employer. The presence or absence of a communicable disease may be objectively determined, and the risk it poses is easily quantified. There are no criminal law consequences to the diagnosis of a communicable disease, so there is no need for protection against self- incrimination in disease screening. In many cases, treatment will eradicate the condition. Even when treatment is impossible, only rare circumstances demand more than minimal workplace restrictions to prevent the spread of the disease. When these restrictions are required, they are solely to protect others, not to punish the affected individual.