In Mr. Flynn’s case, acknowledging that he has records related to contacts with the Russian government may be incriminating because his response to the subpoena could be used to establish his knowledge of their contents and prevent him from denying his connection to the transactions described in them. Thus, his act of producing documents could incriminate him, so he can refuse to turn them over to the Intelligence Committee.

That is not the end of the analysis, however, because there are three ways in which the government could still obtain the records — but none are particularly appealing.

First, the Fisher decision contains an important caveat to the availability of the Fifth Amendment to avoid producing documents. If the government can show their existence, possession and authenticity is a “foregone conclusion” so that investigators will not learn anything valuable from the act of production, then the privilege against self-incrimination dissipates and the records must be produced.

This is often a difficult standard to meet and the burden would be on the government to show it knew what records Mr. Flynn had in his possession and that they were authentic. Absent that proof when the subpoena was issued, he can then assert the Fifth Amendment to refuse to turn them over.

A second means to obtain records would be for Congress to ask the Justice Department to authorize immunity for the act of production, which would overcome the privilege against self-incrimination and require Mr. Flynn to turn the records over.

But that is perilous, as the prosecution of Webb Hubbell, the former associate attorney general, showed. Immunity covers not just actual use of the records produced pursuant to a subpoena, but also any “derivative” information gained from them.

After Mr. Hubbell pleaded guilty in 1994 to mail fraud and tax charges for overbilling clients in his private practice, the independent counsel investigating President Clinton subpoenaed additional records from him to see if he was being paid to remain silent about possible misconduct in the Whitewater matter.