Whether the Court had to decide whether the admissions were involuntary and therefore barred by the Fifth Amendment before setting aside the convictions.
Holding
No. The Court declined to reach the constitutional voluntariness question because the admissions were independently inadmissible under the Court's supervisory authority over federal criminal procedure.
Reasoning
The Court acknowledged that a conviction cannot rest on evidence obtained in violation of fundamental constitutional liberties. It also recognized prior decisions invalidating convictions based on confessions extracted through coercive questioning or unlawful incommunicado detention. But the Court concluded that it need not determine whether the McNabbs' admissions crossed the constitutional line into involuntariness.
Review of federal convictions is broader than the Court's limited constitutional review of state convictions. In federal cases, the Supreme Court has supervisory responsibility to establish and preserve fair standards of evidence and procedure in federal criminal trials. Those standards may require exclusion even when the Constitution does not itself compel that result.