In the earlier Arizona case there was a federal law that specifically denies the states the authority to enforce immigration laws without the approval of the Feds.
There is no law authorizing what Obama is doing now.
It is based on a concept- prosecutorial discretion- which may, or may not, be supported by a court.
But see that’s the thing, he hasn’t actually done anything.
he said he was going to issue an order, but he didn’t.
So as far as I know, he is simply still not enforcing existin glaw, which has already been upheld as far as I know.