Donald Trump has resuscitated questions regarding Texas Senator Ted Cruz’s eligibility to serve as president of the United States. Cruz was born in Canada to a Cuban father and an American mother. A recent Trump tweet succinctly pressed the issue: “Sadly, there is no way that Ted Cruz can continue running in the Republican primary unless he can erase doubt on eligibility. Dems will sue.”

The U.S. Constitution requires that the president be a “natural-born citizen” of the United States. Though many contend that being born to an American mother is sufficient, others say only those born on U.S. soil are eligible.

What would a legal challenge to Cruz’s eligibility look like? It’s far more complicated than you might think because it depends on how each state handles his access to the ballot. New Hampshire’s Ballot Law Commission, for example, has already said that Cruz is eligible — at least until a court says otherwise.

Scenario A: Could someone sue to try to keep Cruz off the ballot? Such challenges are unlikely to succeed. A plaintiff must have standing to sue and must show a specific injury rather than a generalized grievance. Voters can’t just complain that someone, somewhere is violating a law — they have to identify an actual harm. Most challenges to candidates’ eligibility end here. Federal courts, for example, threw out dozens of birther challenges to Barack Obama’s eligibility in 2008 and 2012 because voters sued and failed to identify a concrete injury. So, the courts never had to rule that Obama was actually born in Hawaii.

State courts are not bound by the federal standards and have heard challenges from such voters. But these claims often fail because states are not required to look at a candidate’s qualifications. New Hampshire is an outlier: Many states don’t look at whether a candidate is eligible to be president before placing him or her on the ballot. They accept the paperwork — and happily accept the filing fee — then list the candidate on the ballot. Socialist Workers Party candidate Róger Calero, for example, appeared on several ballots around the country in 2004 and again in 2008 — despite being a Nicaraguan citizen.

Other challenges fail because courts defer to the political process. In a presidential election, one court concluded in a challenge to Obama’s eligibility, it is first left to presidential electors to determine eligibility, and then to Congress when it counts the votes. In addition, candidates may lose elections, which would negate any need for a court to interfere.

Some courts, reluctant to intervene, move particularly slowly and let the election process work itself out.

Scenario B: But what if a state kept Cruz off the primary ballot? What if an election official decided that state law permitted only natural-born citizens to appear on the ballot and concluded that Cruz was ineligible, and thus removed him from the ballot? Or what if a state secretary of state decided to reject votes cast for Cruz in a primary election? Cruz would presumably sue — and he would certainly have standing.

A court may choose to drag its feet and hope that the political process would work itself out. Perhaps, Cruz would drop out of the race before a court reached a decision. But denying voters the chance to vote for an eligible candidate, or refusing to count ballots cast for a candidate, would be a serious harm, and a court would likely weigh in.

A court might simply avoid the harder issue of defining “natural-born citizen” and find reasons to allow him on the ballot. It might conclude that no state law authorizes an election official to scrutinize a candidate’s eligibility, as occurred in some challenges to Obama’s eligibility. Or a court might conclude that a political primary is not binding on the Republican National Convention — since a brokered convention could sort out any prospective nominees’ eligibility questions. A court might also say that this is simply a primary race, not the presidential election itself. So any decisions about his eligibility would be premature.

Accordingly, even if a state left Cruz off the ballot, there are many possible avenues by which a court might order him back on the ballot without addressing whether or not he is a natural-born citizen.

Scenario C: But what if a court does weigh in on Cruz’s eligibility? Unlikely as it might seem, given the many contingencies outlined above, it remains a distinct possibility with a less-than-certain outcome.

Two major positions stand out in the effort to define “natural-born citizen.” Some have argued that the term can only mean a person born within the United States. They cite early British practice before the American Revolution as the principle codified in the text of the Constitution.

Others — more persuasively, in my view — argue that Congress, like the British parliament at the time of the founding fathers, has the power to define who is a natural- born citizen at birth. British and early U.S. practices help demonstrate this understanding.

In 1952, Congress enacted a law granting citizenship to anyone born to an American mother who met a few conditions of domicile in the United States. Cruz is a citizen under that law. And whether he is natural-born turns on whether Congress has the power to declare him natural-born.

How a court resolves this debate is highly uncertain. As courts have generally shied away from resolving disputes about candidate qualifications, judicial involvement here would be truly unprecedented.

Scenario D: Even after all this, there remains one still more potential outcome: a brokered convention. Trump, or some other candidate, might choose to challenge Cruz’s eligibility at the Republican National Convention. Challenges to delegates pledged to support Cruz would claim that such delegates could not vote for an unqualified candidate. And the Republican National Committee would have to sift through these contests, potentially leading to a brokered convention in which no single candidate earned a majority of the delegates’ votes on the first ballot.

That could lead to far greater uncertainty: Who in the party would be able to broker a deal about who should be the Republican nominee? There would also likely be a fresh round of debates on the term “natural-born citizen.” This scenario would be extraordinarily unlikely. But in a high-profile contest between Trump and Cruz, perhaps nothing should surprise us.