Impeachment has become a political ploy in today’s rough-and-tumble Washington. Democrats are accusing Republicans of planning it against President Barack Obama. Many of these partisans then use that argument to energize a liberal base in pursuit of fundraising for midterm elections.

House Speaker John Boehner, R-Ohio, has flatly said he doesn’t intend to pursue impeachment. He’s followed the same path as former Speaker Nancy Pelosi, D-Calif., who said seven years ago that she wouldn’t countenance such talk when some progressives began bandying the idea of the impeachment of President George W. Bush. Still, there are some on the right wing at this time that nonetheless seem energized by the idea of using impeachment to their own advantage.

It is instructive to note, on this 40th anniversary of the resignation of President Richard M. Nixon on Aug. 9, 1974, how dramatically things have changed. Politics was no less nasty, but impeachment was too serious a remedy to be bandied about haphazardly in Washington.

It had been tried only once, in the messy aftermath of the Civil War — itself an extraordinary and disastrous one-time event in U.S. history.

Looking back 40 years ago today, we see that impeachment has been threatened or used many times since Nixon, including threats against Ronald Reagan, George W. Bush and Barack Obama. Indeed, Bill Clinton was impeached by a Republican-controlled House. But he survived a Senate trial that failed to convict. That episode appears to have led to the now-conventional wisdom — however contorted — that surviving impeachment might not be that bad. That is argued on the theory that an impeachment episode becomes disastrous to the approval rating of the opposing party that initiates it.

The nation has dumbed down impeachment, as Princeton professor Julian Zelizer wrote recently for “Impeachment will lose its legitimacy within the public if it becomes a totally politicized process,” he wrote.

Fortunately, the seriousness of this constitutional remedy still imposes strong barriers against a full-blown impeachment hearing. The leadership of both parties has been sober enough to keep impeachment from degenerating into a no-confidence vote in a parliamentary system. Still, the incessant talk about it does no favors for public confidence in our political processes.

Watergate bestowed several important lessons upon this nation. One of them is that it takes real criminal action, on the scale of ordering break-ins, paying hush money and ordering IRS investigations into political enemies, to push politicians into real action. Even then, they will act only if the public mood demands this ultimate action.

Impeachment is the last resort in a representative government. If carried through to a successful conclusion, it would negate the will of the people as expressed in an election. Even with opinion polls showing a lack of support for Nixon, his resignation was a tragic moment in American history.

To bandy about impeachment threats today as a political ploy is an insult to that history and a disservice to the electorate.