Hugo Black

“ In fact, the last visit of the revenue agent to the jail to question petitioner took place only eight days before the full-fledged criminal investigation concededly began. And as the investigating revenue agent was compelled to admit, there was always the possibility during his investigation that his work would end up in a criminal prosecution. We reject the contention that tax investigations are immune from the Miranda requirements for warnings to be given a person in custody. ”

“ These differences are too minor and shadowy to justify a departure from the well-considered conclusions of Miranda with reference to warnings to be given to a person held in custody.
It is true that a 'routine tax investigation' may be initiated for the purpose of a civil action rather than criminal prosecution. To this extent tax investigations differ from investigations of murder, robbery, and other crimes. But tax investigations frequently lead to criminal prosecutions, just as the one here did. ”