The arc of partisanship in impeachment, to some extent, matches the increased polarization of politics in America over the last 45 years. It moves from consensus to deadlock.

When the House Judiciary Committee votes on articles of impeachment against President Trump, the vote is expected to be along purely partisan lines — a far cry from the committee impeachment vote against President Richard Nixon in 1974, and different too from the President Bill Clinton's impeachment in 1998.

Back in 1972, it wasn't the break-in at the Democratic headquarters that triggered the Nixon impeachment inquiry. It wasn't even the Senate Watergate Committee hearings that riveted the nation a year later. It was the Saturday Night Massacre, when President Nixon fired special prosecutor Archibald Cox and shut down his investigation.

"Constitutional Crisis"

"The country tonight is in the midst of what may be the most serious constitutional crisis in its history," intoned NBC's John Chancellor on the Nightly News after the attorney general resigned rather than carry out the firing order and the deputy refused, only to be fired. Ultimately, Solicitor General Robert Bork would carry out Nixon's orders. But it was all for naught.

Public opinion soon forced Nixon to name a new special prosecutor, Leon Jaworski, who continued the probe, eventually turning over subpoenaed White House tape recordings and other damning information to the House Judiciary Committee.

On February 6, 1974, the U.S. House of Representatives, by a staggering vote of 410-to-4, authorized the House Judiciary Committee to begin an impeachment inquiry.

A "Weak" Chairman?

The chairman of the committee was Representative Peter Rodino, D-N.J., new in the post, and untested.

He would, within months, become a national hero for his handling of the historic hearings.

"Rodino's insight was that for the American people to accept impeachment, should it go in that direction, it would have to be a bipartisan impeachment," says Timothy Naftali, the founding director of the Richard Nixon Presidential Library and a co-author of Impeachment: An American History.

"Around Peter Rodino were a group of committee chairs who didn't really respect him," continues Naftali. "I'm talking about fellow Democrats. They thought he was too weak."

And they, along with some in the party's left wing, wanted to impeach Nixon not just for abuse of power and obstruction of justice. There were lots of other charges on the table. Serious charges. Nixon's personal tax-evasion scheme, his secret bombing of Cambodia, and more.

"Rodino decides he can't work with those impeachers. He decides he needs his own team," says Naftali.

Rodino recruited a separate impeachment staff of about 100 led by two respected Republican lawyers, John Doar, known for his civil rights work in the Justice Department during the Kennedy and Johnson administrations, and Chicago lawyer Albert Jenner.

Throughout, Rodino had to balance his own party's factions--the liberals on the one hand, and on the other, the conservative Democrats from the Deep South, worried about upsetting their constituents.

And he wanted support from Republicans and was prepared to give them what they asked for. When Republican members wanted to hear from witnesses who had testified before the Senate Watergate Committee, Rodino said yes to closed-door testimony, and President Nixon's lawyer was allowed to participate. Nixon, however, continued to stonewall. And his GOP allies in Congress were not happy.

"The White House gets pressure from House Republicans because the White House is not assisting the inquiry, and when it reaches the point where the White House just won't turn over tapes, the Committee votes to subpoena a president for the first time," recounts Naftali. "Only three Republicans voted against that subpoena."

"Let's Throw All This Stuff ... Up In The Air"

As the committee moved toward a public debate on articles of impeachment that summer, the youngest member of the committee, at age 32, was freshman Republican Bill Cohen of Maine.

"Just before we were supposed to go public, Tom Railsback called me and said, 'Why don't you come on up to my office tomorrow morning, have coffee and some doughnuts and let's see what's gonna happen when we go public,'" Cohen recalls. "And I said, 'Who's gonna be there?' He said, 'I have no idea. But I'd like you to come.'"

Railsback was a well-liked and respected Republican from a conservative district in Illinois. And when Cohen showed up he was surprised to see who else was there. Among the seven were Caldwell Butler, a conservative Republican from Virginia, who would play a leading role in the unfolding drama, and Walter Flowers a conservative Democrat from Alabama, who had at one time managed George Wallace's campaign for governor.

"Walter Flowers in his true Southern drawl said, 'Look, let's throw all this stuff we've been listening to up in the air and see what falls and what we can all agree to.' We listed all the things that troubled us individually, and then we said, 'Well, it's abuse of power and obstruction of justice.' Those two articles we all agreed upon," and agreed to argue for in the coming debate, Cohen says.

Behind the scenes there was enormous stress. Flowers would develop a bleeding ulcer and would be in considerable pain. Railsback, the organizer of the group, would lose his voice — Cohen thinks for psychological reasons. Railsback felt greatly indebted to President Nixon for sending federal agents to find his missing daughter at some earlier time.

When it came time for the vote, the committee rejected three articles of impeachment — the tax evasion charge and another were considered personal, not an abuse of presidential power. The secret Cambodian bombing was considered a policy difference. Two articles — obstruction of justice and abuse of power — were approved by an overwhelming, bipartisan vote. A third — failure to comply with the impeachment inquiry's subpoenas — passed by a narrower margin.

Just days afterward, when Nixon obeyed a Supreme Court order to turn over the remaining tapes subpoenaed by the special prosecutor, it was all over. The famous "smoking gun" tape showed Nixon trying to enlist the CIA to sabotage the FBI investigation. Support among House Republicans completely collapsed. Those who had voted against the articles of impeachment in committee, changed their votes.

And Nixon resigned.

Americans breathed a sigh of relief, and told themselves that the system had worked, the Constitution had triumphed over rampant presidential abuse of power.

But Naftali has a warning about the Nixon impeachment proceedings. What if Nixon had continued stonewalling the committee. What if he had not been forced to turnover the tapes to the special prosecutor, and the prosecutor had not turned them over to the House? "The Constitution seems to imply that somehow the House is going to get what it needs to figure out the right thing to do for the country," Naftali observes. But there is no guarantee of that, as President Trump has demonstrated.

The Clinton Impeachment

Nearly a quarter century after Nixon's forced resignation, there was far less consensus, and more partisanship when Republicans voted to impeach President Clinton for lying under oath about his affair with a 22-year-old White House intern.

This time the House Judiciary Committee chairman was Republican Henry Hyde of Illinois.

"The matter before the House is a question of lying under oath . . . of the willful, premeditated, deliberate corruption of the nation's system of justice," Hyde declared at the time.

Massachusetts Rep. Barney Frank, then the ranking Democrat on the Judiciary Committee, recalls that his Democratic colleagues thought initially that Clinton was cooked.

"Members of the Democratic caucus were anticipating being pressured to vote to get rid of him by their constituents," says Frank. "And the opposite happened. Public reaction with our constituents was: you don't impeach a guy for this."

Democrats didn't want to impeach Clinton, but they didn't want to exonerate him either. So they decided to move to censure him. Some Republicans favored the idea, too, and there were even negotiations to do something more than censure — to require, for instance that Clinton pay a fine or make a formal admission.

But the GOP House whip, Tom Delay of Texas, nicknamed "The Hammer," had been driving the impeachment hard behind the scenes, and he didn't want to give any Republicans an out. So he maneuvered the House rules to prevent a vote on censure on the House floor.

The House, mainly but not entirely along party lines, approved two articles of impeachment — for perjury before a grand jury, and obstruction of justice. But two other impeachment articles approved by the Judiciary Committee failed by significant and bipartisan margins.

"Compelling, Overwhelming, And Bipartisan"

Twenty-one years later, the lesson that House Speaker Nancy Pelosi took from the Clinton impeachment was that unless she could get some Republican buy in, the effort was doomed.

"She said, in fact, it ought to be compelling, overwhelming, and bipartisan," says New York Times reporter Peter Baker, a co-author of Impeachment: An American History.

"They do think it's compelling, and they do think it's overwhelming. But they don't have the bipartisan," adds Baker. "And it may be that it's impossible in this day and age to get to bipartisan."

Indeed, the political transformation over the last 45 years has seen moderate Republicans and conservative Democrats become almost extinct. Extreme partisan gerrymandering has ushered in an era in which members of Congress from both parties are less worried about winning over swing voters than they are about a primary opponent from the base of their own party.

Impeachment In An Era Of Hyper-Partisanship

So, in the modern political world, where Fox News and MSNBC often feed the warring partisan camps, and where misinformation is often peddled by social media, does this mean that impeachment and removal from office is a dead letter? Does it mean that impeachment, rarely used, but often threatened, will no longer be something of a check on presidential power?

When the founding fathers wrote the Constitution, the country was in "an undue period of optimism," says Stephen Presser, emeritus professor of law at Northwestern University. And even though the framers very deliberately gave Congress the power of impeachment as a check on the chief executive, they "really didn't see political parties nationwide arising...they saw local factions, but they never thought that we would reach the point where we are today."

Short of an actual impeachment inquiry, there have in fact been many impeachment threats over the years. Among the more recent, George H.W. Bush worried about impeachment if he went into the Gulf War without congressional approval, notes Times reporter Baker.

"So from the beginning of the republic 'til today, impeachment has served as kind of a deterrent against bad behavior," Baker observes. "But if the lesson of this comes out that, hey, you're always going to be okay as long as your own party sticks with you, that changes that dynamic I think."

Of course, nothing is entirely predictable. In 1998 Republicans confidently expected to add as many as two dozen house seats to their majority in the November election. Instead, they lost four. Two years later California's James Rogan, one of the Republican impeachment House managers, was beaten by a state senator named Adam Schiff, now the chairman of the House Intelligence Committee, which conducted the Trump impeachment inquiry.

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