They have.So far, the courts are ruling against him - aside from some of the firings cases.
And he appears to have been ignoring them in some cases.
One court even ordered them to provide proof that the funds had been restored.
The Supreme Court weighed in and waived that deadline, which means we will soon see if the Supreme Court is going to say the Administration can't be bound by lower court orders (in this case, they will say, letting the exceptions trickle out one by one if this is the route they are taking.)
And, of course, we have Senators and the VP starting to weigh in with the idea that the Executive branch shouldn't have to obey the courts.
So we will see how this plays out.