Bill Cohen served as an influential three-term U.S. senator, as well as secretary of defense, and is a respected global thinker. He believes his defining political moment was a summer four decades ago.

As a 33-year-old freshman Republican representative from Maine, he was a central figure in the House Judiciary Committee's vote on July 27, 1974, to impeach President Richard Nixon.

It was one of the most important and high-minded deliberations in congressional history. Unfortunately, it failed to become a model for subsequent actions. The impeachment of President Bill Clinton and the calls to do so for George W. Bush and now Barack Obama are petty and frivolous by comparison.

Cohen recalls members struggling with the impeachment standard of "high crimes and misdemeanors." As with Elizabeth Drew's compelling 1975 account, “Washington Journal: Reporting Watergate and Richard Nixon’s Downfall,” which was recently reissued, Cohen's recollections are a reminder that American politicians can rise and respond to crises.

Cohen, who ignored advice in 1972 not to go on the Judiciary Committee because "it doesn't do anything," notes that lawmakers were devoid of precedents -- and could look only to English law and the politically tainted effort to impeach President Andrew Johnson more than a century earlier...