Overstepping one's authority

I'm going to assess an argument one might run across among some conservatives. I'm not attributing this to any particular individual. The argument goes like this: 

i) On the one hand, the Federal judiciary exceeded its authority when it ruled a certain way (pick your case).

ii) On the other hand, that ruling is the law of the land. We must abide by it while we work to reverse it by getting more conservative justices on the bench. 

My point is not to exactly represent any individual's argument, but to clarify the argument. To sort out and spell out the kind of argument one sometimes runs across, by separating the two elements of the argument, and comparing them side-by-side.

And if you do that, these two strands of the argument stand in conflict. If any official or gov't agency exceeds its authority, we don't normally say, "But that's the law!"

After all, to exceed their authority is to overstep their legal authority. Isn't that the very definition of an unlawful, lawless, or extralegal directive? They lack a legal basis for their assertion. 

For instance, I believe you normally need a warrant to wiretap the communications of an American citizen on US soil. Suppose your supervisor in the FBI, CIA (or whatever) orders you to conduct an illegal wiretap.

He's exceeded his authority. Since he doesn't have the authority to give that order, it is not a lawful order. 

Same thing with police who sometimes issue lawless orders to private citizens. Now, as a practical matter, you may not be in a position to safely disregard the command. You might comply at the time, then challenge it in court–if the alternative is getting shot.

But I'm making a point of principle. In a situation like that, you have no legal obligation to comply. But isn't that analogous to people who say certain judicial rulings  exceed the authority of the judicial branch?

If that's the case, then how can that be the "law of the land"? How can there be a legal obligation to submit to a ruling if the judiciary overstepped its Constitutional authority? How is that different in principle from the examples I gave?

I'm just responding to conservatives who might say that a particular ruling represents an abuse of power, transgressing the Constitutional prerogatives of the court, yet that's binding on private citizens as well as the other two branches of gov't, unless and until it is overturned by the court. 

These two arguments don't go together. You can relieve the tension by dropping one or the other. But in combination, they are incoherent.