We’re still waiting to find out why special counsel Robert Mueller decided not to take a position on whether President Trump obstructed justice in connection with investigations into possible Russia interference in the 2016 election. And while that question seems likely to be at least partially answered when a redacted version of Mueller’s report is released by Attorney General William Barr, the debate over whether Trump obstructed justice is far from over.

The evidence in Mueller’s report and his reasoning for not coming to a conclusion on the obstruction of justice question will help set the battle lines. But remember, Mueller was focused on whether Trump committed the crime of obstruction of justice, which can be difficult to prove. And Barr determined that the evidence against Trump didn’t meet the legal standard for that crime. However, in the political world, where two past presidents have faced impeachment over allegations that they obstructed justice, the standard for determining presidential wrongdoing is much murkier.

Depending on what’s in the report and how much of it is released, Trump’s critics may be able to argue that even though he was not charged with a crime, he should still face political consequences — whether it’s more congressional investigations, impeachment or a loss at the ballot box in 2020. But the issues that make an obstruction of justice case hard to prosecute — in particular, the difficulty of proving intent to obstruct justice — won’t go away in a political context. In fact, the lack of clarity about what obstruction of justice means outside of the legal realm could make for another politically messy showdown.

Why obstruction of justice can be difficult to prove legally

One big, unresolved question is whether Mueller’s report will contain new information about potentially obstructive behavior by Trump. The media has previously reported on other presidential behavior that could be viewed as obstruction, including Trump’s firing of FBI Director James Comey and the circumstances that led up to it; Trump’s attacks on then-Attorney General Jeff Sessions over Sessions’s decision to recuse himself from the Russia investigation; and the possible dictation by Trump of a misleading statement about Donald Trump Jr.’s June 2016 meeting at Trump Tower with a lawyer linked to the Russian government.

All of these actions could, arguably, be evidence that Trump was trying to stymie the Russia investigation. But they could also be explained in ways that wouldn’t satisfy the criminal standard for obstruction of justice, which hinges on whether “corrupt intent” can be proved. In the absence of more obvious forms of obstruction like destroying evidence or instructing witnesses to lie under oath, Trump’s motivations and state of mind become crucial. Laurie Levenson, a former federal prosecutor and law professor at Loyola Law School Los Angeles, told me that because Mueller never interviewed Trump, meeting this burden of proof is particularly tough, as it’s very difficult to clarify the reasoning behind his actions without talking to him.

There’s also an argument — embraced by the president’s lawyers and at least at one point by Barr — that the president can’t commit obstruction of justice by firing members of the administration or issuing pardons, because that’s part of his official constitutional power as president. This is a controversial stance, and we don’t know whether it affected Mueller’s decision-making or Barr’s conclusion that the obstruction of justice evidence didn’t support criminal charges. The one thing that is clear is that the Justice Department will not be charging the president with obstruction of justice (which was always something of an unlikely scenario because of longstanding department policy against indicting a sitting president). That means what we have now is a situation in which Mueller’s evidence and prosecutorial analysis — produced as part of a criminal investigation — will set the stage for a political fight in Congress about whether Trump’s conduct makes him unfit to be president.

How a political obstruction of justice case could unfold

To understand what it might take to make a successful political obstruction of justice case, we can look to the situations surrounding two previous presidents who faced impeachment over allegations that they obstructed justice — Bill Clinton and Richard Nixon.

Neither president had been charged with a crime at the time impeachment articles against them were approved by the House Judiciary Committee. But in Nixon’s case, that wasn’t because of an absence of evidence — court documents unsealed last year revealed that a grand jury was ready to charge him with four criminal counts in connection with the Watergate break-in and cover-up, including obstruction of justice. For Clinton, it wasn’t clear that the evidence was solid enough to support a criminal obstruction charge, but that didn’t stop the Republican-controlled House of Representatives from impeaching him on charges of perjury and obstruction of justice. Clinton was ultimately acquitted by the Senate and left office with high approval ratings, but that doesn’t mean the House didn’t have the right to impeach him. (Nixon resigned before he could be impeached.)

The constitutional standard for impeachment is “treason, bribery, or other high crimes and misdemeanors,” but what the framers meant by “high crimes and misdemeanors” has been up for debate since George Washington’s presidency. “It’s not like James Madison wrote down a list of impeachable offenses on a cocktail napkin and we just lost the napkin,” said Joshua Matz, a constitutional lawyer and the co-author of “To End a Presidency: The Power of Impeachment.” According to Matz, impeachment is not a punishment for something the president did in the past — it’s intended to be deployed in situations in which his conduct poses substantial and ongoing risk to the country. However, he added that “what specific behavior falls into that category is an open question.”

In theory, this means that the standards for proving that a president committed obstruction of justice are different — and arguably lower — when it comes to impeachment, as opposed to a criminal case. And that’s because legislators thinking about impeachment can consider other factors — like potential harm to the country — that wouldn’t be relevant in a criminal context. But Clinton’s case shows that on a practical level, efforts to remove presidents can easily falter if they don’t have a convincing case for wrongdoing, which facts and analysis from a criminal investigation can bolster or undermine. And the political system imposes its own limits — like a Republican-controlled Senate that has shown little appetite for crossing Trump.

There are other political consequences for Trump beyond impeachment, of course. Further evidence that Trump may have tried to interfere with Mueller’s investigation could give House Democrats another excuse to probe his motivations — for example, potential financial conflicts of interest. But factors like intent will likely still matter for convincing the public that Trump is unfit for office or worthy of further investigation. “It will be difficult to meet the impeachment standard without convincing the public that he’s a bad-faith actor,” Matz said. A new and shocking revelation — e.g., that Trump successfully interfered with Mueller’s probe — could help make that case. But in the absence of compelling new evidence, the political bar for obstruction of justice will likely remain high, particularly when it comes to impeachment.

Trump calls Mueller probe an ‘attempted coup’