The inquiry that could lead to US president Donald Trump’s impeachment is complex and moving fast. So fast, in fact, that it’s leaving many of us confused. And one question that looms above them all is this one: Did Trump actually break the law?

If only it were an easy question to answer. But here we go.

First, a quick recap: Trump called the new president of Ukraine on July 25. Someone within the intelligence community (we’re calling this person the ‘whistleblower’) heard the call and was concerned enough to report it to his boss, who agreed that things said in the call were problematic, and kicked it up the chain to the director of national intelligence.

The reason for all the concern? In the call Trump appears to pressure the Ukrainian president to investigate the family of a political rival, former vice president and current presidential candidate Joe Biden. The president may have even stalled funds apportioned by Congress to support Ukraine’s military to increase that pressure.

That is why Trump is now facing possible impeachment.

So after a two-year-long investigation into the Trump campaign’s ties to Russian interference in the US election, and the president’s efforts to obstruct that investigation, and the dramatic unveiling of the final report by special counsel Robert Mueller, and then Mueller’s own testimony before Congress, and a myriad of other potential offenses, this phone call to Ukraine is what finally spurred the Democrats to start the process of impeachment.

But why, after everything, is this the thing that rises to the level of impeachment? It’s a good question.

Why is the Ukraine call more impeachable than all the other accusations against Trump?

The Constitution allows three reasons for Congress to impeach the president: treason, bribery, and high crimes and misdemeanors. Most impeachment cases fall into the third group, and so does this one. It’s the one bucket that doesn’t necessarily require an offense that is against the law.

In the past 200 years, and through 19 impeachment cases (of which three were of presidents), in fact, analysts and observers have interpreted the impeachment process as independent from criminal law. Most scholars agree that to be impeachable, an offense does not need to break the law. There only needs to be the political will. That is, there only needs to be enough votes in the House to impeach, and then in the Senate to remove the president from office.

While pretty much any action could be an impeachable offense if lawmakers agree that it falls under one of those categories, the Ukraine call is outstanding because of the clarity of both the evidence and the offense. In short, the Ukraine call is impeachable because House leadership believes it has enough evidence of wrongdoing to garner enough votes.

The alleged offense is that Trump enlisted the help of another country in his campaign for a second term. There is plenty of evidence for this. Investigators have records of the phone call, Trump’s own admission, and the admission of his private attorney, Rudy Giuliani.

Kenneth McCallion, a former federal prosecutor and expert on counterintelligence operations who authored Treason and Betrayal, the Rise and Fall of Individual 1, told Quartz the problem is clear: “You have abuse of presidential power for personal and campaign use,” he said. But is the problem problematic enough to impeach?

The answer to that question is divided along pretty clear political lines.

Trump’s defenders, nearly all Republicans, don’t think so. They don’t deny Trump’s actions. They can’t because the evidence is overwhelming. Instead, they argue that the offense is simply not that offensive, and not worthy of impeachment or removal from office.

Democrats are equally united on the other side. They believe that Trump using his office to persuade a foreign government to help him attack a political rival is an impeachable abuse of office.

It’s worth noting that while the Ukraine call finally convinced Democrats to launch impeachment proceedings, the House of Representatives can put multiple “articles” of impeachment to a vote. In this context, “articles” essentially mean “charges.” Lawmakers can vote to impeach the president on the basis of any number of offenses. So there could be articles of impeachment pertaining to actions prior to the Ukraine call as well, including obstruction of justice during the Mueller investigation. One article could be “contempt of Congress” if Trump refuses to cooperate.

The House only needs a simple majority on one of the articles to trigger an impeachment trial in the Senate. Once it gets to the Senate, Trump defense attorneys would make arguments on one side and members of the House on the other. Chief justice of the Supreme Court John Roberts would act as judge. In the end, Trump would be removed from office only if two-thirds of the Senate voted to convict. That’s an unlikely result because Republicans remain in control of the Senate, and ultimately impeachment proceedings are a political process rather than a criminal one.

The whole process would be a lot easier on Democrats if they didn’t have to rely on perceptions of wrongdoing but instead on the letter of the law. But did Trump break the law? That claim is more difficult for Democrats to argue because, well, there is no clear law on the matter.

Did the president break any laws?

To be impeachable, a presidential action does not need to break a law. Still, in this case, his actions might have. If the investigation found that Trump abused his position to gain competitive advantage over his adversary in the election, that would amount to soliciting a valuable contribution to his campaign from a foreign entity, which is forbidden by campaign finance laws. In order to be a criminal violation, a contribution needs to be more than $2,000. But for it to be a civil violation, any amount—monetary or otherwise—will do.

“There are specific campaign laws which prohibit any US citizen, whether it be the president or otherwise, from receiving a benefit or a value from a foreign party,” McCallion said.

So whether or not Trump broke those laws will depend on how lawmakers interpret “value.” Those who support impeachment say Trump was clearly seeking something of value from Ukraine, namely, opposition research on Biden.

That’s made worse by the fact that Trump used military aid in his negotiation, leveraging not his personal fortune, but taxpayer money as a bargaining chip to pressure Ukraine’s president. Since the American government had voted to give the money to Ukraine, Trump withholding it to solicit information that would benefit himself strengthens the argument of the abuse of power, adding another layer of misconduct.

So if Trump asked Ukraine for information on anyone other than a rival candidate, would it be unlawful?

It wouldn’t break campaign finance laws. But it would still be problematic because it bypasses the lawful process to deal with such situations.

“If in fact the Department of Justice had a bonafide investigation of criminal activity and reached out to a foreign government, that would be OK,” McCallion said. But it’s one thing to have an official investigation from the Justice Department, and another thing to go rogue, using private citizens.

“In this case you have the president having authorized a private individual, Rudy Giuliani, outside any government accountability, to run basically a private or personal investigation,” McCallion said, adding that this is outside any due process.

“The phone call was through these private parties to further the goals of the Trump 2020 campaign,” McCallion said.

Even if the objective wasn’t to advance his career, the president can’t just personally pursue justice through private citizens outside his administration. While maybe not as egregious an an abuse of power, such behavior is problematic and shows contempt of due process, said Martin Flaherty, a law professor at Fordham and Princeton.

“The ordinary way is to go through the department of justice,” Flaherty told Quartz. “The president acted outside the internal executive guidelines.”

But is acting outside of accepted guidelines a crime? It’s not.

The president taking action independently from the justice department isn’t something that happens frequently, and certainly not to dig up dirt on a political rival. Still, there isn’t a statutory law prohibiting the president from personally handling legal concerns, even seeking the help of a foreign authority to gather information on someone believed to be involved in a crime. In fact, it isn’t even a crime if the person in question is a politician—and when it is a political rival, the only criminal laws it might break are campaign laws.

In the end, whether or not Trump broke a law will come down to how elected lawmakers interpret campaign finance laws. If they don’t think a law was broken, Trump could still be impeached. But only if lawmakers think the offense rises to the level of “high crimes and misdemeanors.” In today’s political climate, however, it will likely just come down to who holds the majority, Republicans or Democrats.