Presidents have invoked executive privilege on the ground that disclosing information sought would impair the functioning of the Presidency.

The President invoked the patriotism of the dead.

The President did not not invoke executive privilege at any time during his testimony, and there were no serious disagreements over classified documents.

The implication was that the President would not invoke the act under any circumstances.

We did not have one instance in which the President invoked executive privilege.

In the Senate, an amendment directing the President to invoke the statute failed by a vote of 50 to 41.

But he said that he did not know whether the President had formally invoked the privilege in court.

The issue of when a President may invoke executive privilege has a long but vague legal history.

"Unless the President invokes martial law to protect the country and takes control of the computers until we can respond."

In its decision, the court sidestepped the indictment issue while deciding that the President could not invoke executive privilege to shield the tapes.