Polygraph Law and Legal Definition

Polygraph refers to instrumentation to test or question individuals for the purpose of detecting deception or verifying truth of statements. A polygraph examiner is any person who purports to be able to detect deception or verify truth of statements through instrumentation or the use of a mechanical device. State laws, which vary by state, often require the licensing of anyone who administers polygraph examinations or holds himself out as a polygraph examiner.

There has been considerable debate on whether polygraph results should be admitted as evidence in court. Polygraph results are no longer barred from the courtroom. The Supreme Court has left it to the courts of each jurisdiction to determine how and when to allow it, or to exclude it altogether.