Today, in AARP v. Trump, the Supreme Court issued a ruling blocking deportation of a group of Venezuelan migrants the Trump Administration had been trying to use the Alien Enemies Act of 1798 deport to imprisonment in El Salvador. The AEA allows detention and deportation of foreign citizens of relevant states (including legal immigrants, as well as illegal ones) "[w]henever there is a declared war between the United States and any foreign nation or government, or any invasion or predatory incursion is perpetrated, attempted, or threatened against the territory of the United States by any foreign nation or government."
The Supreme Court's latest ruling doesn't address the issue of whether the administration's invocation of the AEA is legal, though multiple lower courts have ruled it is not, because there is no war, "invasion," or "predatory incursion" going on (only one badly flawed ruling goes the other way on "predatory incursion"). Instead, a 7-2 majority holds only that Venezuelan detainees slated for deportation under the AEA in the Northern District of Texas are entitled to a temporary injunction blocking deportation, because they were not granted adequate notice:
