As we will discuss in class Wednesday, a very important procedural point in Marbury v. Madison is that Marbury filed his suit directly in the Supreme Court, as an "original action." ("Original" because the suit originated in the Supreme Court itself.) As a result, the extent of the Supreme Court's jurisdiction to hear original actions is critical to resolving the case, at least as the legal issues were framed by the Court. And this original jurisdiction is addressed in the Constitution in Article III, section 2, clause 2.
When you examine that clause, you will see that it makes reference to "Ambassadors [and] other public Ministers and Consuls." Today, we might well think of the Secretary of State, the defendant in Marbury, as a "public minister." But the meaning in Article III is narrower than it would be in modern parlance: it refers specifically to representatives of foreign governments. Thus, as everyone agreed at the time, Secretary of State James Madison was not a "public minister" for purposes of Article III.
This point is important to following Chief Justice Marshall's reasoning in Marbury. I intended to mention it at the end of class but forgot.