John Doe (D) was a target of a federal grand jury investigation over the fraudulent manipulation of oil cargoes and receipt of unreported income. D appeared before a grand jury, produced records, and testified that no additional banking records were within his possession. When questioned of additional records, D took the Fifth. Grand jury subpoenas were then issued to United States Branches of the banks, but the banks refused to comply as their governments' laws prohibited disclosure of account records without customer consent. The prosecutor then filed a motion that D be ordered to sign a consent form. D refused to sign on self-incrimination grounds. The District Court denied the motion by the United States (P), reasoning that, by signing the consent forms, D would necessarily be admitting the existence of the accounts. Compelling D to sign would be to compel D 'to perform a testimonial act that would entail admission of knowledge of the contents of potentially incriminating documents,' and such compulsion was prohibited by the Fifth Amendment. P sought reconsideration. The Court of Appeals for the Fifth Circuit reversed because the form 'did not have testimonial significance,' and therefore its compelled execution would not violate Doe's Fifth Amendment rights. The Supreme Court granted certiorari.