On Wednesday, five active members of the armed forces brought a challenge to Trump’s announced ban. Each of them has already joined the military, is serving honorably, and has come out to their commanders as trans, in reliance on the explicit Department of Defense policy permitting them to serve openly. Even before the ban becomes official, each is suffering its ill effects, in terms of career uncertainty. That should be enough to grant them standing.

They are represented by lawyers for two advocacy groups—LGBTQ Legal Advocates & Defenders and the National Center for Lesbian Rights—and a dream team of heavyweight attorneys from two major law firms, Foley Hoag and WilmerHale.

There’s little law directly on this point, because we’ve never had a president who issues policies in 140 characters—and not since Andrew Johnson have we had one so willing to use the office so impulsively as a club against disfavored people and groups. But I think they have a pretty good chance of blocking the ban. Defense Department lawyer Michel Paradis, writing as a private citizen in Lawfare, agrees.

Trump must have felt quite confident in issuing his ukase. Under the Constitution, the president is “commander in chief of the army and navy of the United States.” That power is more sweeping than almost any other in the document. The commander-in-chief role has, over the years, inspired near-religious deference not only from military officers but also from members of Congress and federal judges. For example, the Supreme Court in 1996 approved a military-justice statute that gave the president a remarkable role in capital cases. When it came to defendants in the military, Congress authorized the president by regulation to decide what factors should determine whether they should be executed. That kind of criminal law is usually made by legislatures; this kind of delegation would never be tolerated in civilian courts. Justice John Paul Stevens wrote that in matters of military justice “it would be contrary to the respect owed the president as commander in chief to hold that he may not be given wide discretion and authority”—even in the area of life and death.

In part because of this tradition of deference, presidents regard the military as their property. “Son, they’re all my helicopters,” Lyndon Johnson once told an airman; Trump said he had announced the transgender ban “after consultation with my generals and military experts.” But the Constitution is very clear: Congress, not the president, has the exclusive power “to declare war,” “to raise and support armies,” “to provide and maintain a navy,” and “to make rules for the government and regulation of the land and naval forces.”

They’re all Congress’ helicopters. The president just gets to borrow them.

Over six decades, courts have held that congressional “government and regulation” of the military must follow constitutional standards. Judges aren’t about to second-guess genuine command decisions, such as deployment orders. Courts can and sometimes do, however, protect the individual rights of men and women in the ranks. Those in the military have fewer rights than civilians, but they have rights nonetheless.