The petitioner was convicted by a jury on two counts of violating the federal wagering tax law, §§ 4411 and 4412 of the Internal Revenue Code of 1954, 26 U.S.C. §§ 4411, 4412. His conviction was affirmed by the Court of Appeals for the First Circuit, 301 F.2d 314. The petitioner contends that his conviction should have been reversed because at his trial the prosecutor was permitted to ask two witnesses incriminating questions concerning their relationship with the petitioner, with the knowledge that the witnesses would invoke their privilege against self-incrimination. We granted certiorari to resolve an asserted conflict with decisions in other circuits. 371 U.S. 858, 83 S.Ct. 115, 9 L.Ed.2d 97.
The theory of the prosecution's case was that the petitioner had operated a small gambling ring in Chelsea, Massachusetts. His method of operation, according to the Government's theory, was to visit several neighborhood stores at regular times each day for the purpose of collecting betting receipts and paying off winning bets. One of the shops he visited was a variety store owned by Irving and Annette Kahn.
Informations charging violations of the federal wagering tax laws were filed against the petitioner and the Kahns on the same day. All three were represented by the same lawyer, John H. Fitzgerald, and all three pleaded not guilty. On the day of the petitioner's trial, the Kahns changed their pleas to guilty. Because they had previously told government investigators that the petitioner had collected the wagers made in their store and had personally settled accounts with them, the Kahns were subpoenaed to appear at the petitioner's trial.
In his opening statement to the jury, the prosecuting attorney stated that he had reason to believe 'a husband and wife' would testify against the petitioner. Upon the completion of the opening statement, Mr. Fitzgerald approached the bench, and the following colloquy took place:
'Mr. FITZGERALD: Your Honor, it is my understanding that the United States Attorney is going to attempt to use the Kahns as witnesses.
'Now, keeping in mind that they are defendants, that they are entitled not to testify in their own case-
'The COURT: They have pleaded guilty.
'MR. FITZGERALD: I know that, your Honor, but still I didn't waive any Constitutional privileges in their behalf.
'The COURT: I think the law is that they have no Constitutional privileges after they have pleaded.
'MR. FITZGERALD: Your Honor, further that they are under investigation by the Internal Revenue Department as far as their income taxes are concerned, and everything else.
'The COURT: Well, I haven't seen them take the stand yet, and if they claim the Fifth, I will rule on it then.'
After brief testimony by the first government witness, the United States called Annette Kahn. Mr. Fitzgerald repeated his objection for the record, but made no further arguments. Mrs. Kahn then testified to her name, her address, the ownership of the store, and her acquaintance with the petitioner. She refused to answer whether she and her husband had 'some type of business relationship' with the petitioner. An extended colloquy at the bench ensued. The court eventually concluded that Mrs. Kahn's plea of guilty to the charge of engaging in the business of accepting wagers deprived her of the right to refuse to testify about her own gambling activity. But the court also ruled that she did not have to testify about any dealings with third persons since she was still, at least theoretically, subject to prosecution for conspiracy, or possibly bribery. Mr. Fitzgerald made no new objections or arguments during this colloquy. To the contrary, he appeared to acquiesce in the questioning of Mrs. Kahn in open court once he had managed to work out a convenient means for advising her when to assert her privilege against self-incrimination.
The questioning of Mrs. Kahn was resumed after a brief recess. The prosecuting attorney began a line of questioning designed to determine whether Mrs. Kahn had known of the gambling tax requirement before the date of her arrest. Mr. Fitzgerald objected, on the ground that the questions were not material. Another conference at the bench was held, in which the prosecuting attorney explained that his purpose was to show that Mrs. Kahn was not in danger of a conspiracy charge. The court sustained Mr. Fitzgerald's objection to the materiality of the questions. The interrogation was then discontinued.