The Supreme Court did not. Only Chief Justice Taney issuing his ruling from the Circuit Court bench said Lincoln could not. The entire court never took the matter up.
You are correct that the entire Supreme Court did not hear this case, but I think you are wrong that Chief Justice Taney issued the ruling from the Circuit Court. One of the lawyers who used to post on FreeRepublic noted that it was issued as an in-chambers ruling, not a district court ruling. Our lawyer friend said the following in a post:
"The famous opinion in Ex Parte Merryman, the one delivered to President Lincoln, issued from the Supreme Court. In was an in-chambers opinion of Chief Justice Taney acting in his capacity as Chief Justice of the Supreme Court. ,,, Technically, he did not issue it in his capacity as a judge "on circuit" but rather as an "in chambers" opinion of the chief justice."
Whichever way it was, a district court order or an order issued as chief justice, it was a valid court order that Lincoln ignored. If Lincoln wanted it overturned, he could have appealed to one court or the other. He didn't. I suspect he knew he would lose.
At the time this was being discussed on FreeRepublic years ago, another lawyer poster who is now dead, I believe, sent me the following by Freepmail"
In HIS decision, Taney writes:
"Before THE CHIEF JUSTICE OF THE SUPREME COURT of the United States, at Chambers."
"The application in this case for a writ of habeas corpus is made to ME..."
"I resolved to hear it in the latter city..."
"...a habeas corpus is served on the commanding officer, requiring him to produce the prisoner before A JUSTICE OF THE SUPREME COURT..."
"As the case comes before ME ..."
"I shall, therefore, order all the proceedings in this case, with MY opinion, to be filed and recorded in the Circuit Court of the United States for the District of Maryland..." "CHIEF JUSTICE OF THE SUPREME COURT of the United States..."
District Court Judge Giles had already had a habeas corpus writ turned down by Lincoln's military, Perhaps Giles suggested to Merryman's counsel to go discus the case with Taney. Anyway, Taney showed up in the District Court.
My first lawyer friend then posted the following and gave a reference:
"As he took his place he announced that he acted alone rather than with Judge Giles because of the fact that he was sitting not as a member of the circuit court, but as Chief Justice of the United States. One reason for the distinction, undoubtedly, was the belief that it would lend added weight to the decision."
"-- Carl Brent Swisher, Roger B. Taney, The MacMillan Company, published October 1935, reprint June 1936, pp. 551."
In another old newspaper covering the case, I later found mention of Taney saying in court during the proceedings that Judge Giles had no say in the case or something to that effect.