The matter (habeas corpus) had not come before the full court (except perhaps under Marshall), but it did come before the Chief Justice of the Supreme Court. As you no doubt know, single Supreme Court Justices can issue rulings by themselves.
It was proper that the writ be issued by Chief Justice Taney. This was an emergency matter since a habeas corpus writ issued by the Maryland District Court had already been disobeyed by the army that same month. The District Court was powerless to confront the army.
Several weeks earlier on May 4, 1861, Judge Giles of the Maryland District Court had issued a writ of habeas corpus that was disobeyed by the commander of Fort McHenry in Baltimore. The power of the army had already overridden the legitimate functioning civil court, the Maryland District Court. What good would it have done to issue another District Court ruling that would also get disobeyed? That was probably why the petition for the writ went directly to Taney, not the District Court.
The law said that Justices of the Supreme Court could issue writs of habeas corpus. From the Judiciary Act of 1789:
Section 14.
And be it further enacted, That all the before-mentioned courts of the United States, shall have power to issue writs of scire facias, habeas corpus, and all other writs not specially provided for by statute, which may be necessary for the exercise of their respective jurisdictions, and agreeable to the principles and usages of law. And that either of the justices of the supreme court, as well as judges of the district courts, shall have power to grant writs of habeas corpus for the purpose of an inquiry into the cause of commitment.——Provided, That writs of habeas corpus shall in no case extend to prisoners in gaol, unless where they are in custody, under or by colour of the authority of the United States, or are committed for trial before some court of the same, or are necessary to be brought into court to testify.
Chief Justice Taney himself declared in court in the Merryman case [Source: The Baltimore Sun, May 29, 1861]:
Chief Justice Taney, upon taking his seat on the bench, said that he desired to state that his associate, Judge Giles, of the Circuit Court, was present with him yesterday by his invitation, because he desired to avail himself of his counsel and advice in so important a case. The writ of habeas corpus was ordered by him as Chief Justice of the Supreme Court of the United States, consequently Judge Giles could not act with him in the case.
If the writ were a District Court matter, then Judge Giles could act with Taney. But Taney stated that Giles couldn't so act with him. The writ was not a writ of the District Court -- it was a writ issued by a Justice of the Supreme Court. If such a writ were disobeyed, logic says the response (Ex parte Merryman) was the act of Justice of the Supreme Court who issued the writ, not the District Court which Taney said could not act with him in this case.
It did not come before full court under Chief Justice Marshall, it has never come before the full Supreme Court under any Chief Justice. And the only time a single justice can issue a ruling by himself is if he is sitting on the circuit court bench, as Taney was.
It was proper that the writ be issued by Chief Justice Taney. This was an emergency matter since a habeas corpus writ issued by the Maryland District Court had already been disobeyed by the army that same month. The District Court was powerless to confront the army.
Habeas corpus had been suspended in the Baltimore area by the president, so Taney's issuing the writ was invalid.
Habeas corpus definately came before the full court under Marshall. The case was Ex Parte Bollman and Swartwout. Bollman and Swartwout were two Aaron Burr associates who were arrested in New Orleans for their involvement in the 1807 Burr-Wilkinson conspiracy. The case arose out of the activities of Wilkinson in New Orleans, who blocked delivery of a territorial Federal Judge's habeas corpus writ to Swartwout just long enough to get him on a transport ship to Washington, D.C. for trial. Wilkinson was arguing that the danger to New Orleans posed by Burr's loyalists required him to arrest conspirators without the writ. Marshall found that the writ had not been properly suspended though, and ruled that the Supreme Court had to grant it to the two prisoners.
It's a very important early supreme court case because it has defined how habeas corpus applies ever since. Unfortunately our dumbass Attorney General Alberto Gonzales has apparently never read it, which is why the Bush administration keeps getting slapped down in court over Gitmo. And it's not that they're doing anything wrong either - they're just making the wrong legal arguments and erroniously designating the prisoners with the cloak of civilian rights to conform to their misguided legal arguments. If they followed Ex Parte Bollman and the similarly important Ex Parte Milligan from 1866, instead of the highly flawed Ex Parte Quirin from 1941, they could detain the Gitmo thugs as booked POW's and war criminals long as they wanted and the leftist whiners couldn't do a damn thing about it.