The Democratic caucus in the House of Representatives suddenly seems to be careening toward impeachment. The resistance to this measure, led by House Speaker Nancy Pelosi, appears to be crumbling in the face of the new scandal over President Trump’s bullying of Ukrainian President Volodymyr Zelensky to produce damaging information on Joe Biden and his son. Whether the newfound momentum will sustain itself over the coming days is anyone’s guess. But the sudden and urgent focus on impeachment raises an important question: What should the House impeach President Trump for? If the House is no longer considering whether to impeach Trump and has really decided to move forward, it needs to think about what articles of impeachment should—and should not—contain.

This is actually a difficult question. Trump’s misconduct presents what the military calls a target-rich environment. There’s a huge range of activity that a reasonable member of Congress could in good conscience regard as impeachable. That said, it would be a very bad idea for the House to take the approach of throwing a lot of spaghetti at the wall and seeing what, if anything, sticks. That approach could potentially trigger political blowback, giving the president’s allies more material with which to portray congressional Democrats as just a bunch of crazed and partisan attack dogs. And it could also risk doing real institutional damage. When Congress passes an article of impeachment, it makes a statement about the nature of offenses that justify removal from office. It is important to be careful when making such statements so as not to create ill-considered precedents that will justify future mischief.

This is why it is critically important to be disciplined at this juncture—to base articles of impeachment only on that activity which is not merely a plausible basis for removal but is unambiguously justified as a basis for removal. That means that anything that is a matter of policy—no matter how much one might disagree with the policy or how abhorrent one might find it—should not be included. For example, Congress should strongly resist the temptation to include disputes over border security—including both spending on the wall and the grotesque policy of family separation—in any articles it might draw up.

It also means that Congress should avoid issues that implicate Trump’s conduct before he became president. Whether pre-presidential conduct can ever be impeachable is an interesting question; the answer is probably that it can under certain extraordinary circumstances. (One of us has argued as much regarding payments made to Stormy Daniels and Karen McDougal during the campaign.) But, here, there is not a good reason for Congress to force that difficult question. For impeachment purposes, Trump should get a mulligan on misconduct that took place while he was a candidate. That means not including wrongdoing associated with Russia’s intervention in the 2016 election—most of which does not overtly implicate Trump’s personal conduct anyway. It also means ignoring for impeachment purposes Trump’s likely criminality with respect to the Daniels and McDougal payments. While this activity spilled over into his presidency, it is predominantly pre-presidential.

There’s another reason to leave this particular material out, independent of its merits as a potentially impeachable offense: During the Clinton impeachment, Democrats presented themselves as taking the principled view that a president shouldn’t be removed for modest criminality to cover up sexual indiscretion. Unless they want the impeachment debate to focus on their flip-flop, they would do well not to flip-flop on that.

Additionally, while reports that Trump has suggested he would pardon officials in order to induce lawbreaking certainly strike at the heart of impeachable conduct, the current record is insufficiently strong. Because press reports remain unconfirmed, and because the comments are open to interpretations that the president was speaking in jest, Congress should, for now, not include this conduct.

Finally, articles of impeachment should not include alleged violations of the Emoluments Clause in connection with the operation of the Trump Organization’s many commercial properties. This activity, while gross and while definitely implicating Trump’s behavior as president, is of genuinely contested constitutional status. What’s more, Trump has done it out in the open, and Congress has remedies well short of impeachment that it hasn’t bothered to exercise to address it. It would be unwise to impeach the president over a disputed point of constitutional law when Congress has not even sought to take plainly available steps—like passing laws, for example—to prohibit the offensive activity. Impeachment is a last resort, not a step the House should take because a legislative coalition is not available.

In short, Congress should focus for impeachment purposes only on matters of unacceptable presidential conduct that are provable on the basis of currently available evidence and that are thus easily presentable to the Senate for judgment.

This does not mean that Trump’s conduct outside this category is wise, moral, acceptable or even, in some cases, legal. But the House must rigorously focus on the worst provable offenses undertaken as president in part because there are so many possible charges to begin with. Some of these are very bad but not impeachable; some might conceivably justify impeachment in and of themselves. But incorporating everything will ensure that nothing receives the full attention that it warrants. The House thus needs to focus on those offenses that make the strongest case of misuse of presidential power, rather than wading into difficult questions concerning the impeachability of pre-presidential conduct, sexual misconduct, racism or other moral failures.

What does that leave in terms of impeachable conduct? A lot.

We think Congress should focus its impeachment consideration—if, indeed, it now means to conduct a formal impeachment inquiry—on five major areas, each of which could easily support an article of impeachment.

The first is obstruction of justice and abuse of law enforcement institutions and personnel. This basket covers the president’s efforts to impede the special counsel investigation of Russian interference in the election and the campaign against the FBI those efforts entailed. Even if one believes that firing FBI Director James Comey was a wholly legitimate move, the president didn’t stop there. He also attempted to dissuade witnesses, specifically Paul Manafort, Michael Flynn and Michael Cohen, from cooperating with federal authorities. He attempted to corruptly persuade Attorney General Jeff Sessions to limit the scope of the investigation and to reverse his decision to recuse himself from personal involvement in the face of conflicts. He attempted to limit the investigation by pressuring Deputy Attorney General Rod Rosenstein to fire the special counsel. And he endeavored to have White House Counsel Don McGahn create a false record regarding Trump’s actions with respect to efforts to fire Robert Mueller.

It is true that the Mueller report establishes other conduct that Congress could reasonably conclude qualifies as obstruction of justice for impeachment purposes. But the above describes those broad areas in which the evidence most clearly establishes that the president acted with a corrupt purpose and in a manner that exceeded the scope of his Article II powers.

The articles of impeachment drawn up against both Richard Nixon and Bill Clinton contained similar allegations. In Nixon’s case, the first article adopted by the House Judiciary Committee found that Nixon had “engaged personally and through his close subordinates and agents, in a course of conduct or plan designed to delay, impede, and obstruct the investigation” into the Watergate burglary; “to cover up, conceal and protect those responsible; and to conceal the existence and scope of other unlawful covert activities.” In Clinton’s case, both articles of impeachment adopted by the full House of Representatives touched on obstruction: One article accused Clinton of perjury, with the goal of “willfully corrupt[ing] and manipulat[ing] the judicial process of the United States for his personal gain and exoneration,” while the second directly concerned obstruction of the Paula Jones sexual harassment litigation against him.

The second broad area also concerns abuse of law enforcement power, but in a different sense. Whereas the first basket focuses on Trump’s efforts to obstruct an existing investigation, the second involves his attempts to leverage the power of the presidency to cause investigation and prosecution of political opponents. This includes Trump’s request to then-Attorney General Jeff Sessions to—as the Mueller report describes—“reverse his recusal so that Sessions could direct the Department of Justice to investigate and prosecute Hillary Clinton.” There is a substantial evidentiary record concerning this type of misconduct: Mueller cites directly to testimony given by Sessions to the special counsel’s office, and there is a lengthy record as well of public statements by the president—also included in the Mueller report—expressing dissatisfaction with the Justice Department for its failure to investigate Clinton.

Trump’s 2016 opponent is far from the only person he has targeted in this fashion. He has repeatedly and publicly accused FBI Director James Comey of crimes and has asked why the Justice Department has not investigated and prosecuted Comey. And he has done the same for former FBI employees Peter Strzok and Lisa Page, along with—among others—Justice Department official Bruce Ohr, Ohr’s wife, former CIA Director John Brennan, former Director of National Intelligence James Clapper and Clinton campaign manager John Podesta. And as Mueller notes in the report, Trump also appeared to threaten prosecution of Michael Cohen’s wife and father-in-law after Cohen began cooperating with the Mueller investigation—threats that Mueller understood as potentially “an effort to retaliate against Cohen and chill further testimony adverse to the President ….” Finally, and most recently, there are the efforts by the president and his personal lawyer, Rudy Giuliani—both reported on in the press and acknowledged publicly by both Trump and Giuliani—to push not the United States government, but the government of Ukraine, to investigate Democratic presidential candidate Joe Biden and his son Hunter.

This conduct, too, has a parallel to the Nixon impeachment articles. The famous second article of impeachment adopted by the House Judiciary Committee accused Nixon of “repeatedly engag[ing] in conduct violating the constitutional rights of citizens,” in part by seeking to initiate IRS and FBI investigations against his political opponents. This activity, the article states, was “in violation of [Nixon’s] duty to take care that the laws be faithfully executed.”

The third broad area Congress should focus on is the abuse of the president’s foreign policy authorities and misuse of congressionally appropriated money to induce a foreign head of state to violate the civil liberties of U.S. persons and interfere in a presidential election. This basket is less factually developed than the first two, since we have no analog to the Mueller report available and the executive branch is withholding key material relevant to it. That said, the president himself has acknowledged that his July 25 phone conversation with Zelensky concerned “all of the corruption taking place and largely the fact that we don’t want our people like Vice President Biden and his son creating to the corruption already in the Ukraine.” He has also said, confusingly, that “[t]here was no pressure put on [Ukraine] whatsoever. But there was pressure put on with respect to Joe Biden.” His lawyer, Giuliani, has said on CNN that he asked the Ukrainian government to look into the Biden family, after initially denying it. And aid funds to Ukraine were held up while this pressure was taking place. All of that is before you get to specific press reports—which are not yet fully confirmed, but some of which the president himself has acknowledged—that the president leaned on Zelensky eight times in the phone conversation and that the president personally directed that aid to Ukraine be withheld in the days prior to this conversation. An impeachment article focused on L’Affaire Ukrainienne would have some thematic overlap with an article focused on abuse of law enforcement powers, as it involves ginning up law enforcement activity against political opponents. But it also involves other things: “collusion” with a foreign power for purposes of electoral advantage, gross misuse of congressionally appropriated funds, and pressuring a foreign leader for reasons of personal gain rather than public concern.

The fourth area for Congress to focus on in considering impeachment is the president’s efforts to obstruct or impede congressional investigations. This basket includes the president’s evident decision to frustrate congressional oversight of his conduct in general by refusing to comply with subpoenas. On April 24, the president laid the matter bare when he declared, “We’re fighting all the subpoenas.” The White House strategy to effectuate the president’s desire to impede oversight has been to assert novel, overbroad and frequently frivolous claims of executive privilege and absolute immunity. Individually, each of these claims might represent assertions of constitutional prerogatives to be adjudicated by the judicial branch; collectively, however, they represent an assault on the very notion of congressional oversight. That means litigation, yes, but it also means defending the broad proposition that outright presidential defiance of Congress is unacceptable.

The relevant conduct here includes, but is not limited to, the assertion of executive privilege over the testimony of Corey Lewandowski, who has never been a government employee and refused to testify about matters that did not involve his providing advice or counsel to the president anyway; the overbroad assertions of absolute immunity over the testimony of former White House Counsel Don McGahn and others; the overbroad assertion of executive privilege over the testimony of former White House employees Hope Hicks and Annie Donaldson; the direction to the Internal Revenue Service not to comply with clear federal law requiring the production of the president’s tax returns; the interference in efforts to compel third parties to comply with congressional subpoenas to produce tax returns and related financial documents; the direction to the Office of the Director of National Intelligence not to comply with federal law requiring the disclosure of a whistleblower complaint deemed “urgent” and “credible” to relevant congressional committees; the refusal to comply with congressional requests for documents and testimony related to irregularities in the security clearance process; the refusal of Attorney General William Barr and Commerce Secretary Wilbur Ross to comply with congressional subpoenas to produce documents related to the addition of a citizenship question on the census; and the refusal of White House aide Kellyanne Conway to comply with a subpoena to testify regarding the Office of Special Counsel determination that she had violated the Hatch Act numerous times. Again, individually some of these actions might have a plausible defense; in some cases, there are legal arguments to be made in support of the president’s positions. The aggregate pattern, however, is an unacceptable affront to Congress’s ability to conduct investigations and oversight of the executive branch. If Congress does not defend that ability, it will lose it.

Here, too, there is a parallel to Nixon. The last of the three articles of impeachment that grew out of Watergate concerned Nixon’s failure to “produce papers and things as directed by duly authorized subpoenas issued by the Committee on the Judiciary of the House of Representatives,” thus “substituting his judgment as to what materials were necessary for the inquiry … thereby assuming to himself functions and judgments necessary to the exercise of the sole power of impeachment vested by the Constitution in the House of Representatives.”

A final area Congress should examine is Trump’s lying to the American public. The 1974 article of impeachment concerning Nixon’s obstruction of justice also noted his lies to the public about the Watergate investigation: Nixon, the Judiciary Committee charged, made “false or misleading public statements for the purpose of deceiving the people of the United States into believing that a thorough and complete investigation had been conducted” on the Watergate matter and that White House and Nixon campaign officials had no involvement in the burglary. Kenneth Starr also suggested an article of impeachment against Clinton for “mis[leading] the American people,” though Congress declined to adopt this article. Trump has rather outdone prior presidents in the lies department. The Washington Post “Fact Checker” database of presidential dissembling as of Aug. 5 had documented 12,019 “false or misleading statements” by Trump since he took office. The Mueller report documents multiple instances in which the president and administration officials speaking on his behalf knowingly lied to the public. His tenure has genuinely posed the question of whether the president has any obligation at all to tell the truth about anything—ever. His presidency is, among other things, advancing the proposition that the idea of “faithful” execution of the law implies no duty of candor at all.

This is not a question about which Congress should remain neutral. And here impeachment is the only remedy. Congress cannot pass a law demanding that Trump stop lying or tell the truth a higher percentage of the time. It can only vote that lies of such magnitude and nature and frequency as the ones he tells are inconsistent with the conduct of the office he holds.

Focusing an impeachment inquiry on these areas will be frustrating. It will mean that a great deal of maddening conduct—indeed impeachable and even criminal conduct—on the president’s part will necessarily take a back seat. But it is critical to conducting an impeachment process in a defensible and coherent fashion that makes a statement about acceptable presidential behavior. If the House is really moving to consider impeaching the president, it needs to resist the temptation to turn the impeachment process into an indiscriminate expression of any and all grievances. It must ground itself in the provable record. And it needs to make decisions about what message it wants to send about what presidential conduct a coordinate branch will brand as constitutionally intolerable in a person who swears the presidential oath of office.