In the 1971 case LEGO v. Twomey, Warden, the United States Supreme Court ruled on a matter concerning self-incrimination and police interrogation procedures. The petitioner, Lego, was convicted of armed robbery based in part on statements he made to police without counsel present. He argued that his confession should not have been admitted into evidence because it was obtained in violation of Miranda rights and due process protections under the Fifth Amendment. However, the court held that once a trial judge determines at a preliminary hearing that a defendant's confession is voluntary beyond reasonable doubt (the standard for criminal convictions), this finding need only be supported by preponderance of evidence (a lower standard) at trial for admission purposes. This means confessions can be used as long as they are more likely than not to have been given voluntarily - even if there is some doubt about their voluntariness.

The dissenting opinion in the LEGO v. TWOMEY case argued that the majority's decision to uphold Lego's conviction was flawed because it did not adequately consider whether or not his confession had been voluntarily given, which is a requirement under Miranda rights. The dissent pointed out that Lego had requested an attorney multiple times during his interrogation but was denied each time, and he eventually confessed after being told by police officers that they would get him a lawyer only if he first admitted guilt. This coercion, according to the dissenters, violated Lego's Fifth Amendment rights against self-incrimination and rendered his subsequent confession involuntary and therefore inadmissible as evidence. They also criticized the majority for setting too high of a standard for proving involuntariness of confessions at pretrial hearings – beyond reasonable doubt rather than just preponderance of evidence - arguing this could lead to potential abuses by law enforcement officials who might feel emboldened to use coercive tactics during interrogations knowing they are unlikely be held accountable later on.