Which countries are legally allowed to use lie detectors?

The legality of using lie detectors, or polygraphs, varies by country. In the United States, their use is common in specific contexts, such as employment screening and criminal investigations, but results are not typically admissible in court. In the United Kingdom, polygraphs can be used in certain circumstances, such as for monitoring sex offenders, but are not widely accepted in legal settings. Other countries, like Canada and Australia, have more restricted or limited use of polygraphs, primarily for investigative purposes rather than as definitive evidence.