A federal court just shot down a bad argument that President Trump’s lawyers were making. They were trying to quash a subpoena that Democratic prosecutors have cynically filed in reaction to Trump’s bad decision to keep his tax returns secret.

It’s the same vicious cycle of norm-breaking that has become the destructive pattern of the Trump era. It should never have gotten this far.

For starters, Trump should follow the precedent of all the men elected president since Richard Nixon. He should voluntarily release his tax returns.

Openness and transparency are great virtues in government, particularly for executives. This administration has taken some voluntary steps in the name of transparency, including (slightly belatedly) disclosing all the waivers from the administration’s voluntary lobbying restrictions. Transparency by the executive gives the public confidence that the government, and the individuals running the government, are doing things by the book.

Absent that confidence in their government, people begin to suspect everyone is cheating and that everyone in power is abusing it. This lack of trust is the norm in Third World countries, and it is unhealthy.

Also, the perpetuation of voluntary traditions is valuable in its own right. We are conservatives, and we think people shouldn’t need a law or mandate in order to do something. But often, they ought to do things simply because they have always been done before. That creates a sense of continuity that is crucial to a democracy.

The public deserves to know from where Trump is earning his money. The possibility that he has a source of income we don’t know about leaves open the possibility of corruption, and it at least leaves one unnecessary reason why some might believe that there is corruption.

One final downside of refusing to disclose his tax returns publicly: Trump has now invited Democrats to take harmful steps to force him to disclose them.

House Democrats have considered using Congress’s oversight of the IRS simply to yank Trump’s returns. Congress has the power to review individuals’ tax returns as a means of monitoring whether the tax code is working as intended. Yet the use of this power to get the president’s taxes — and inevitably leak them — would be a brazen congressional abuse of power. It would also open the gates for this practice to expand, such that Congress routinely leaks the taxes of political enemies: a presidential candidate of the other party, an opposition leader in Congress, a pesky columnist, pastor, or cable news host. This is a path the nation cannot afford to go down.

But the current Democratic tactic doesn’t involve Congress at all. Cy Vance, a Democratic prosecutor in New York, claims he needs to see Trump’s tax returns in order to investigate whether Trump committed state tax fraud in paying hush money to a porn star as part of an extramarital affair. There is no doubt at all Vance will publicize the tax returns whether or not he ultimately brings charges.

This is a cynical ploy, and it has been met with an even more cynical legal argument by Trump’s team. Trump’s lawyers are asserting that a president’s immunity to criminal prosecution means that state prosecutors are not allowed to subpoena Trump’s accountant. This is an absolute and limitless claim to immunity that has no grounding in precedent, common law, or the Constitution.

It’s no wonder a federal judge shot that argument down. But it’s a shame that Vance's case will go forward, because it’s an equally cynical ploy. In turn, it’s a shame that Vance even has to do this. Trump should have released his taxes. And he should not have allowed himself to get into a position where he had to pay hush money to anyone.

One depth cries out to another. The abandonment of norms by one side in politics inspires the other side to abandon still more norms. This sort of thing is deadly to a free society. For absent norms and ethics, in steps either chaos or the state, and neither is the friend of liberty.