In Jenkins v. Delaware (1968), the U.S Supreme Court ruled on a case involving the admissibility of polygraph test results as evidence in court trials. The defendant, Robert Lee Jenkins, was convicted for first-degree murder based on his confession which he claimed was coerced by police officers after they showed him unfavorable lie detector test results. He appealed to the Supreme Court arguing that his confession should have been excluded from trial because it was induced by an unconstitutional psychological ploy - showing him false polygraph results. The Supreme Court held that since there were no federal standards governing the use of lie detectors and their reliability remained questionable, states had discretion over whether or not to admit such evidence in criminal cases. In this particular instance, Delaware law did not permit admission of polygraph tests into evidence; however, it allowed confessions obtained through its use if voluntarily given. Therefore, Jenkins' conviction stood as long as his confession could be proven voluntary under state law – a matter left up to lower courts to decide upon remand. This ruling underscored both skepticism about scientific validity of lie detectors and deference towards state rules regarding their evidentiary use.

In the dissenting opinion for Jenkins v. Delaware, Justice William O. Douglas argued that the majority's decision to allow a confession obtained after 19 hours of interrogation was in violation of the defendant's Fifth Amendment rights against self-incrimination and his Sixth Amendment right to counsel. He contended that such prolonged questioning is inherently coercive and therefore any resulting confession cannot be considered voluntary or reliable evidence. Furthermore, he criticized the court for failing to establish clear standards regarding when an individual should be advised of their constitutional rights during police interrogations, which he believed left too much discretion in the hands of law enforcement officers who may not always act with impartiality or respect for these rights.