Is President Obama in danger? (Charles Dharapak/AP)

Jonathan Turley, the Shapiro professor of public interest law at George Washington University, has testified in Congress about impeachment and served as lead defense counsel for Judge Thomas Porteous in his Senate impeachment trial.

Some 40 years after Richard Nixon resigned to avoid his likely impeachment by the House of Representatives, Washington is again talking impeachment. Members of Congress are denouncing the president’s contempt for constitutional law, while the president is raising money to fight the effort to remove him. But this time, the money pouring in would be just as well spent on defense against Bigfoot. Much of the debate has been more mythological than constitutional.

1. An impeachable offense is anything Congress says it is.

People pushing for President Obama’s impeachment have cited rationales ranging from the border crisis to Benghazi to Obamacare to the dismantling of “our constitutional republic, our national security, our electoral system, our economic strength, our rights and liberties.” In other words, anything goes. This echoes the characterization by Gerald Ford, who as House minority leader in 1970 made the ill-considered statement that “an impeachable offense is whatever a majority of the House of Representatives considers it to be at a given moment in history.” (This interpretation was, not surprisingly, part of a frivolous effort to impeach Supreme Court Justice William O. Douglas, whom Ford denounced for espousing “liberal opinions,” for defending the “filthy” Swedish film “I Am Curious (Yellow)” and for writing a magazine article that “praises the lusty, lurid, and risque along with the social protest of left-wing folk singers.”)

But Congress’s exclusive power to impeach does not license it to abuse that power, any more than the Supreme Court’s final say on laws gives it license to deliver arbitrary rulings. The framers carefully defined the grounds for impeachment as “treason, bribery, or other high crimes and misdemeanors” — language with British legal precedent. They clearly did not want removal of the president subject to congressional whim. Indeed, they rejected the addition of “maladministration” after James Madison cautioned that “so vague a term will be equivalent to a tenure during pleasure of the Senate.”

It is the standard that justifies the power, not the inverse, as Ford saw it. The fact that only two presidents have been impeached, and none have been removed, suggests that most members of Congress take the impeachment standard seriously.

2. An impeachable offense must involve a violation of criminal law.

While there’s a high bar for what constitutes grounds for impeachment, an offense does not have to be indictable. Serious misconduct or a violation of public trust is enough. Madison saw impeachment as “defending the community against the incapacity, negligence or perfidy of the chief magistrate.” And the founders emphasized that impeachments were about what happened in the political arena: involving “political crimes and misdemeanors” and resulting in “political punishments.”

So consider the $454 million Obama shifted out of the Affordable Care Act’s Prevention and Public Health Fund. He wouldn’t have to pocket that money to warrant impeachment. But he’d have to do more than he did: redirect it to another purpose without congressional approval and offer a faulty interpretation of the act. If the president were to openly defy clear federal authority and order unlawful acts, he would move from the realm of using arguable discretion to that of being a danger to the system as a whole.

3. History establishes a clear precedent for impeachable conduct.

Democrats can’t stop talking about it, and some Republicans would like to drop the issue all together. Here’s the back and forth on whether the GOP is really trying to impeach the president. (Pamela Kirkland/The Washington Post)

Regrettably, this is also untrue. Bill Clinton was impeached primarily for criminal conduct: lying under oath and misleading a federal grand jury about his affair with Monica Lewinsky. Nixon would have been impeached for a wide array of criminal acts, as well as abuses of power.

President Andrew Johnson’s impeachment in 1868 may be the most relevant to the current controversy. Like Obama, Johnson was accused of unconstitutional executive appointments, misuse of federal funds and violating federal law. Most significantly, he replaced Secretary of War Edwin M. Stanton in open defiance of the Tenure of Office Act — a law passed over his veto and later found unconstitutional by the Supreme Court. The feeble merits of his impeachment were captured best in the 10th article, charging Johnson with delivering three speeches that disrespected Congress.

4. Impeaching a president is like recalling a governor.

Many people discuss impeachment as a way to express dissatisfaction or as a mechanism allowing for a change in leadership. “Impeachment is no more or less than the recall of an elected official who isn’t up to the job,” conservative columnists Floyd and Mary Beth Brown wrote. “Obama deserves recall much more than Gov. Gray Davis, and he was replaced by Gov. Arnold Schwarzenegger in a special recall election Oct. 7, 2003, in California.”

In Britain and other parliamentary systems, the legislature can end the term of a head of government early with a no-confidence vote, showing that he or she has lost the support of the country. But the United States rejected that approach in favor of greater stability and the predictability of a four-year presidential term.

It doesn’t matter that polls show more than 50 percent of Americans disapprove of the job Obama is doing. Unpopularity is not an impeachable offense. And impeachment was not designed as relief for voter remorse.

5. Obama is in danger of impeachment.

House Republicans on Wednesday voted to sue Obama for exceeding his constitutional authority when implementing the Affordable Care Act. The idea that the lawsuit is a prelude to impeachment, however, is primarily coming from the White House and its allies as they try to rally the Democratic base ahead of the midterms. House Speaker John Boehner has done everything short of hiring blimps to say that there will be no impeachment.

Obama is as likely to be impeached as he is to be installed as the next pontiff. And I say that as someone who has testified in Congress that this president has violated federal laws, unconstitutionally appointed various executive-branch officers and improperly transferred money. Nevertheless, many of these disputes have divided judges on the merits. Presidents are allowed to challenge Congress in such conflicts without being subject to impeachment. Where they cross the line is when they ignore final judicial rulings in acts of contempt of both courts and Congress. Obama has not done that.

There are, however, serious questions raised by the president’s pledge to go it alone in areas ranging from health care to immigration. And there is a real crisis in how our system is changing with the rise of the uber-presidency. That’s the threat that deserves attention and debate. We can leave this Bigfoot sighting in the wilderness.

Five myths is a weekly feature from The Post’s Outlook section challenging everything you think you know. You may also like: Bob Woodward on new revelations 40 years after Watergate and Jonathan Turley on the rise of the fourth branch of government.