The U.S. Constitution lays out the few requirements for serving as president of the United States: One must be at least 35 years old, a natural-born citizen of the United States, and a resident of the country for at least 14 years. That’s it. With these minimal strictures in place, the voters (and the Electoral College) can have their say over who will lead them. By imposing only minimal requirements, the American system lends itself to openness and democratic deliberation.

America’s most populous state, unfortunately, is now attempting to add another, extra-Constitutional requirement to the list. Under a law just signed by the California’s Democratic governor, Gavin Newsom, in order for a candidate to appear on the state’s presidential primary ballot, he or she will have to publicly release their last five years of tax returns.

Mr. Newsom’s law is plainly directed at just one candidate: President Donald J. Trump.

Despite promising, repeatedly, to release his tax returns, Trump has failed to do so, breaking decades of precedent. We're disappointed in the president's failure to make his taxes public. For one, the president said multiple times he would make the documents public. Secondly, Americans are more in the dark about their president’s finances than they have been about their prior leaders.

Nonetheless, the California law is a mistake. The U.S. Constitution is clear on the requirements for presidents and states should not go around adding their own. If politicians want to change the requirements for running for president, they should seek to amend the Constitution, not pass irresponsible laws at the state level.

Newsom’s law also sets a dangerous precedent that could easily be weaponized by partisans of both sides. What is to stop other states from coming up with other ways to keep a particular candidate off their ballots?

We also worry about the potential for weaponization of tax returns for political ends. Yes, Trump should have released his taxes. But, ultimately, it was his choice to make.

Our laws permit the government access to people’s private lives in order to assess taxes, including into such areas as income, investments, medical expenses and child care. The deal the government made with the public in collecting this information was that it will remain private, not handed over to operatives to seek to use it to damage their political opponents. It is easy to see that the widespread distribution of such data could also subject taxpayers to blackmail or stalking. A state demanding the release of inherently private documents is downright chilling. Would it stop with presidential candidates?

The state’s power to tax is subject to abuse. We have seen in previous administrations attempts to curtail political speech by denying or delaying nonprofit status to potential opponents. Politicizing individuals’ taxes can quickly turn into an assault on our liberty.

Fortunately, it is almost certain that the courts will invalidate the new California law, given that the Constitution lays out very clearly what the requirements are for the presidency, permitting the voters to decide the rest.