Maness v. Meyers
In Maness v. Meyers (1975) 419 U.S. 449, an attorney was held in contempt for advising his client, the defendant in a civil obscenity trial, not to comply, on self-incrimination grounds, with the city attorney's subpoena demanding production of certain magazines.
In addition to assurances that he had no intention of prosecuting, the city attorney argued that the defendant was "amply protected" against self-incrimination "because in any ensuing criminal action he could always move to suppress, or object on Fifth Amendment grounds to the introduction of the magazines into evidence." (Id. at pp. 461-462.)
The Supreme Court rejected this view: "Laying to one side possible waiver problems that might arise if the witness followed that course, , we nevertheless cannot conclude that it would afford adequate protection. Without something more 'he would be compelled to surrender the very protection which the privilege is designed to guarantee.' " (Id. at p. 462.)
In a footnote, the court explained what it meant by "something more":
"It is important here that the witness was not granted immunity from prosecution on the basis of any magazines he might produce. ... Had the witness been granted formal immunity a different case would be presented; in that event a witness may be compelled to testify." (Id. at p. 462, fn. 10.)