Transgressing yet another norm, then-presidential candidate Donald Trump failed to release his tax returns during the 2016 election. Other than Gerald Ford in 1976, Trump is the first presidential candidate in modern history to do so.

The state of California still hasn't recovered from this transgression, passing a law this summer requiring presidential candidates to release five years of their tax returns by the November before the primary election in order to appear on the March ballot. (This was the second time the state tried to enact such a law, after similar legislation was vetoed in 2017 by then-Gov. Jerry Brown).

States should be judicious about using legally questionable tactics to manipulate state election laws to push their agendas.

There are so many lawsuits worth filing, and fights worth having. States should be judicious about using legally questionable tactics to manipulate state election laws to push their agendas. California risks not just a legal defeat here, but also a real political one as well.

Case in point, Trump immediately and predictably sued to have the new rule declared invalid. And on Sept. 19, Trump won the first battle in his ongoing war against the Golden State after U.S. District Court Judge Morrison England Jr. issued a temporary injunction against the implementation of the law. England’s ruling was based, in part, on the question of whether the Ethics in Government Act, a federal statutewhich requires certain financial disclosures, preempts state laws regarding the financial disclosures by federal candidates.

In this new round of California versus the president, Trump won the first skirmish. Democratic states like California should be careful about using state election laws to further a partisan agenda.

The bar is rightfully high. Tax returns can provide voters with important information about the amount and source of the candidates' income, and can tell the public whether the president might face financial conflicts of interest regarding foreign or domestic businesses. A tax return can also give us information about how charitable a person is, whether or not a candidate availed himself of tax loopholes and whether or not he publicly inflated or deflated his net worth.

But just because a law may have good intentions (or even represents good policy) does not mean that it is legal. By the same token, while it would be beneficial for voters to see what is in Trump’s tax returns, pushing past the Constitution to get them is not a wise endeavor. And this is where California may have pushed its luck just a bit too far.

The U.S. Constitution lists the qualifications for presidential candidates: You must be a natural-born U.S. citizen (i.e. born on U.S. soil, not naturalized), a resident of the country for at least 14 years prior to the election and at least 35 years old. We know that states cannot impose additional qualifications on federal candidates. And we know that the Constitution does not say anything about whether a presidential candidate must release her or his tax returns in order to appear on a state ballot.

While it would be beneficial for voters to see what is in Trump’s tax returns, pushing past the Constitution to get them is not a wise endeavor.

But states do have two important roles to play here.

First, the Constitution gives the states the power to choose the manner of picking presidential electors. As legal scholars have argued, this may even include the ability to say that the some voters do not have the right to vote for president.

Second, states do have some power over their ballots. States have an interest in regulating access to their ballots by imposing requirements that are largely viewed as procedural. States can, for instance, implement filing fees and signature requirements to guard against frivolous candidates who would lead to an overcrowded ballot.

The federal constitutional question the California law raises is whether states have the power to force candidates to release their tax returns if they want to appear on the primary election ballot. (California’s law does not have any effect on the general election ballot, perhaps because this would have been a step too far, even for California.) And the best answer to this question is we do not know, but probably not.

We know that California could not, for instance, say that only people who are 40 years of age, or were born in California, or are lawyers, or are affiliated with a religious institution, could appear on the presidential primary ballot. But requiring that only people who release past years of their tax returns appear on the ballot is a closer call. In some ways it looks like a new qualification, which would be unconstitutional. But in other ways, California’s law looks like a ballot access requirement, because anyone can decide to release their taxes. Put another way, this is a group any candidate can decide to join if she or he chooses to do so, and it doesn’t seem nearly as burdensome or substantive as asking a candidate to become a lawyer or join a religious congregation.

The federal suit is far from the only challenge to California’s law. There is a separate suit alleging that the law violates the California Constitution. The California Supreme Court will soon weigh in on that issue. And Trump only needs to win one of the suits — although there is a good chance he will win both.

Even if California’s law is upheld in both the state and federal courts, it likely will not make any difference in the 2020 presidential election. Trump is all but guaranteed the Republican Party nomination with or without appearing on California’s primary ballot. In this way, California’s law seems mostly like an attempt to poke Trump in the eye. States have a role to play in administering elections. But here, California has likely stretched that role beyond its boundaries, potentially threatening its credibility in the many legitimate fights it is waging against Trump.