Rick Perlstein: What Did Nixon Say?

Last month, a federal court ruled that the testimony Richard Nixon made to the Watergate grand jury in the summer of 1975 should be unsealed and released to the public. The decision has the potential to settle finally the question of whether the nation's 37th president was a criminal.

The grand jury testimony, which Nixon gave in San Clemente, was the only time in history he was required by law to be honest about Watergate. And now we will know what he said.

While Nixon was president he refused to testify at the trials of Watergate conspirators or before the Senate Select Committee investigating Watergate. The Constitution, he insisted, forbade it. As the president's lawyer said in 1973, testimony by the president would be "a serious threat to the nature of the presidency as it is created by the Constitution," because it would involve members of the legislative or judicial branches sitting in judgment of the head of the executive branch.

The Constitution did, he allowed, provide for holding the president legally accountable. The method for doing so was impeachment, followed by trial in the Senate. But Nixon never faced that trial — because, 37 years ago Tuesday, he resigned days before it was to take place, in part to avoid just such a grilling...