That is a modern day idea. It was only starting to have currency in the 1860's. The idea current --then-- was that court rulings only applied to the specific case.
And Ex Parte Merryman was not even a case. It was an opinion, and the Executive branch was entitled to its own opinion, by the standard of the day.
Walt
History says otherwise:
" It is emphatically the province and duty of the judicial department to say what the law is. Those who apply the rule to particular cases, must of necessity expound and interpret that rule. If two laws conflict with each other, the courts must decide on the operation of each. So if a law be in opposition to the constitution: if both the law and the constitution apply to a particular case, so that the court must either decide that case conformably to the law, disregarding the constitution; or conformably to the constitution, disregarding the law: the court must determine which of these conflicting rules governs the case. This is of the very essence of judicial duty. If then the courts are to regard the constitution; and the constitution is superior to any ordinary act of the legislature; the constitution, and not such ordinary act, must govern the case to which they both apply...The judicial power of the United States is extended to all cases arising under the constitution." - Marbury v. Madison, 1803
The idea current --then-- was that court rulings only applied to the specific case.
If that is so, then Taney's ruling, which The Lincoln ignored and refused to appeal, applied to The Lincoln's suspension of habeas corpus.
Sure it was. Do you even know what an ex parte ruling is, Walt? It's an application for court action where only "the one party" seeking the action participates. Courts can and do issue rulings in cases of this nature, as happened with Merryman.