What did Donald Trump do today?

He lost the trust of the Supreme Court.

In an exceedingly rare post-midnight order early Saturday morning, the Supreme Court issued an injunction forbidding the Trump administration from removing a number of detainees to El Salvador. As a result, if Trump does remove the affected detainees to his rented offshore prison beyond the reach of the American justice system, it will be in direct and unambiguous violation of an order from the Supreme Court.

It is not especially surprising that the Court issued this injunction. Courts often issue stays, injunctions, restraining orders, or other halts to legal proceedings, simply as a means to make sure they have a chance to weigh the issue before they are overtaken by circumstance. The Supreme Court's order here does not by itself signify anything about how challenges to Trump's immigration policy are likely to go.

But one thing about the order is extremely unusual, other than the justices staying up late to act on it. It compels the Trump administration not to do something it had already promised lower courts it would not do. In virtually any other situation, a stipulation like that from the United States government would be taken at face value—not least because if a rogue government actor did renege on such a promise, that action could be reversed after the fact. But Trump's creation of an extraterritorial Constitutional dead zone makes it impossible to do that.

In other words, the fact that the Supreme Court issued this order at all is strong evidence that most of its members no longer believe that the executive branch of the government can be taken at its word.

It's not clear if the justices were aware that even as they deliberated, buses filled with detainees in the protected class were headed towards an airport in an apparent attempt to break the Trump administration's "promise" before anyone could do anything about it. The buses turned around when the Supreme Court's order was announced.

Why does this matter?

• It's bad if the judiciary doesn't think the executive branch can be trusted.

• It's worse if they shouldn't think the executive branch can be trusted.