For all the headlines about Russian interference in the 2016 presidential election, no hard evidence has come to light, at least publicly, showing that President Trump or his team were involved. But suppose that such evidence did come to light — what would happen if it became clear that Trump or his advisers colluded with the Russians? This isn’t the only type of wrongdoing the investigations could uncover, but it’s among the most serious because it would cast doubt on the legitimacy of the 2016 result. So, is there a process for dealing with a finding that in essence invalidates an election?

When it comes to presidential elections, the answer is: not really. The laws and processes around national elections have grown up in a piecemeal fashion over time, with state and local laws governing the administration of presidential elections. And the Constitution itself focuses more on ensuring stability than on administering elections. As a result, there aren’t clear procedures for how to handle questions of legitimacy after the fact — especially when those questions involve the presidency.

Breaking this down requires taking a step back to think about the origins of the Constitution and the problems it was designed to solve. First off, the American presidency is kind of a strange office. It combines the duties of a head of state with duties of a head of government. (Many countries divide those duties — for example, by having both a president and a prime minister.) The Constitution gives the president the power to lead the executive branch — the responsibility to “take care” that the laws are faithfully executed — and places that person in charge of the military (although Congress retains the power to declare war).

After some rocky years under the Articles of Confederation, many (though not all) political leaders were ready to make tradeoffs, allowing a more powerful central government that could ensure stability. That was one of the reasons for having a national executive under the new system — the Articles of Confederation didn’t have a president, which made it harder to enforce laws, deal with rebellions and forge national policy out of the demands of different states. There were a lot of considerations when figuring out how to select the right person for that new role, however. The substantial power of the office meant that the president needed to be a person of competence and character; to be independent from Congress; and to be able to represent the nation and not just a few states or population centers. Selecting such a person through a direct election was out of the question; it was difficult for many of the founders even to imagine a national election, or that attempting one would achieve the intended goals. Furthermore, disputed elections are, by definition, destabilizing, so the Constitution is designed to maximize the chances of a conclusive outcome, particularly for the nation’s most powerful office, the presidency.

The framers gave the Electoral College broad discretion to resolve disputes as it saw fit: The text of the Constitution pretty much says an election is legitimate when the Electoral College says it is. It doesn’t lay out a process for do-overs. Occasionally, courts have ordered new elections for offices other than the presidency after a proven case of fraud or error. (Or gerrymandering — a court in North Carolina ordered new state legislative elections, though this order has been put on hold.) And a Senate election was once redone in New Hampshire because it was too close to determine even with multiple recounts.

But whether this kind of re-do is allowed for presidential elections is a more complicated matter. Some legal scholars maintain that the language in Article II of the Constitution prevents holding a presidential election again, thus putting it beyond the power of the courts to order a re-vote, as they have occasionally done for other offices. Others suggest that there is legal precedent for a presidential re-vote if there were flaws in the process. One instance in which this question arose was the “butterfly ballot” from the 2000 election, which may have caused some voters to choose Pat Buchanan when they meant to vote for Al Gore in Palm Beach County, Florida.

If the 2000 election had taken some different twists and turns, the re-vote question might have come up in a serious way, and it’s not clear what the courts would have decided. At least one federal court has suggested that the courts could order a new election. In 1976, a District Court in New York heard a case alleging voter fraud in several urban locations. The court’s opinion maintained that federal courts had a role to play in ensuring free and fair presidential elections, arguing: “It is difficult to imagine a more damaging blow to public confidence in the electoral process than the election of a President whose margin of victory was provided by fraudulent registration or voting, ballot-stuffing or other illegal means.” This assertion challenged the idea that presidential elections occupy a special category beyond such court remedies. However, in this case, the court didn’t find sufficient evidence that voter fraud had altered the outcome, or even occurred at all. As a result, its claims about presidential elections were not evaluated by higher courts and have never really been tested.

So experts disagree about whether courts can order presidential elections to be held again. That’s not great news for angry people hoping for a do-over. And even if it is constitutionally permissible, there’s much broader agreement that the standard for invalidating an election result and holding another vote is quite high. University of Memphis law professor Steven Mulroy told me that courts will usually entertain this option only if they determine a violation of rules that would change the election outcome. In the case of the 2016 election, this would likely require proving tampering in several states where the vote was close — enough to change the result in the Electoral College. In that case, a few states would vote again, not the entire country, Mulroy said. But this is new territory, and no one knows for sure.

It’s worth noting that the U.S. has been through a number of challenging presidential elections. The 1800 election ended in an Electoral College tie, and some politicians mulled over the possibility of holding a new election. Critics alleged that the 1824 election was decided through a “corrupt bargain” among elites, allowing John Quincy Adams to become president even though he won neither the popular vote nor the electoral vote. The election of 1876 had irregularities (including alleged vote suppression) in several Southern states, and an imbalanced commission ended up handing the Electoral College vote to Rutherford B. Hayes even though he had lost the popular vote. People are still debating John F. Kennedy’s razor-thin margin in 1960, the honesty of the votes in Texas and Illinois that year, and even Richard Nixon’s decision not to challenge the results. And, of course, the 2000 election presented lots of problems — confusing ballots, hanging chads, questions about recounts. Each of these instances was different from the questions hanging over 2016, but they offer some context for how our system handles questions of electoral legitimacy.

Sometimes these questions seriously undermine a presidency, as it did with John Quincy Adams and to a lesser extent Hayes, who had already promised to serve only one term. Other times the noise fades from the public conversation and governing proceeds, fulfilling the constitutional goal of stability rather than months (or more) of electoral disputes.

In most of the historical cases, the main question was how the Electoral College votes would be allocated in each state. Once those have been cast, the case for questioning a presidential election or gauging which side really won becomes a lot more difficult. Of course, the Constitution does have one mechanism for undoing the results of an election: impeachment. That process, however, is focused on individual wrongdoing (or, through a separate process, inability), not electoral irregularities. In that sense, even if collusion revelations did lead to Trump’s impeachment and removal from office, the process wouldn’t really address the question of whether his election had been legitimate in the first place.

The lack of an established process for reviewing elections points to a larger issue: The structures established by the Constitution assumed a world in which the presidency and the Electoral College were not fully absorbed into a contentious national party system. That vision has long since been replaced by one in which presidential elections are national contests over policy agendas and ideas. The text of our Constitution has never been changed to reflect this reality. Instead, the Electoral College remains the final word on who gets to be president. When it comes to the possibility that the winning side colluded with a foreign power to influence the election outcome, the Constitution doesn’t offer much in the way of a plan.