"Based on the case law analyzed above, state or federal laws that require drug tests as a condition of receiving governmental benefits without regard to an individualized suspicion of illicit drug use may be susceptible to constitutional challenge. Drug tests historically have been considered searches for the purposes of the Fourth Amendment. The reasonableness of searches generally requires individualized suspicion, unless the government can show a special need warranting a deviation from the norm. However, governmental benefit programs like TANF, SNAP, unemployment compensation, and housing assistance do not naturally evoke the special needs that the Supreme Court has recognized in the past.
"The implementation of governmental assistance programs and the receipt of their benefits do not raise similar public safety concerns as those at issue in Skinner and Von Raab. In implementing these programs, the government also does not clearly act as tutor or guardian for minors, as the Court considered important in Earls and Vernonia. Finally, the evidence, at least thus far, in Lebron has failed to show a pervasive drug problem in the subset of the population subjected to suspicionless testing that strengthened the government’s interests in Earls and Vernonia. Thus, if lawmakers wish to pursue the objective of reducing the likelihood of taxpayer funds going to individuals who abuse drugs through drug testing, legislation that only requires individuals to submit to a drug test based on an individualized suspicion of drug use is less likely to run afoul of the Fourth Amendment.94"
Carpenter, David H., "Constitutional Analysis of Suspicionless Drug Testing Requirements for the Receipt of Governmental Benefits," Congressional Research Service (Washington, DC: Library of Congress, January 19, 2012), p. 12.