Over the last fifty years, courts and scholars have debated the utility and reliability of informants—individuals who alert law enforcement to the occurrence of crime, point law enforcement in the direction of potential perpetrators, and help law enforcement prosecute those eventually charged. There are three primary types of criminal justice informants: (1) criminal and confidential informants, (2) anonymous tipsters, and (3) citizen-informants. Judicial examinations and scholarly critiques of informants have focused almost exclusively on the first two categories. These informants are deemed suspect, either because they are so enmeshed in the justice system that they have questionable motives, or because they inculpate others under a veil of anonymity. Meanwhile, the third category of informant—the citizen-informant—has evaded rigorous scrutiny because of the “citizen-informant doctrine,” a premise embraced by the federal courts and many state courts. The citizen-informant doctrine reasons that individuals who witness or fall victim to crime and willingly identify themselves to law enforcement officers are presumptively reliable. This presumption enables law enforcement officers to conduct searches and seizures that would otherwise be unlawful based on uncorroborated reports from untested civilians. The citizen-informant doctrine has major consequences for the robustness of the Fourth Amendment’s protection against unjustified government intrusions, and it has an enormous impact on the integrity of police investigations and criminal prosecutions. Yet this doctrine rests on shaky foundations that have heretofore been insufficiently probed. This Note proposes that courts require law enforcement officers to conduct more exacting inquiries before relying on the word of a so-called citizen-informant.