US Courts of Appeals - What are the roles of the Circuit Justices?

Question

I was reading the Wikipedia page for the U.S. Court of Appeals for the Second Circuit when I noticed that a "Circuit Justice" (in this case, Ruth Bader Ginsburg) was mentioned.

I then found the page concerning Circuit Justices on the Supreme Court Website. However, while this page lists the Circuit Justices, it does not explain their role.

I also searched the Wikipedia page for United States courts of appeals but did not find any mentions of Circuit Justices, except in the section on the history of the courts, which did not explain what Circuit Justices do in the present day.

My question is, as stated in the title: What are the roles of Circuit Justices?

I would also like to know how Circuit Justices are appointed and why they exist.

Answer 1

A circuit justice is the Supreme Court justice in charge of overseeing a particular appeals court circuit. Such a justice is the first line of contact if a Supreme Court stay is desired. They help by blocking egregiously wrong circuit decisions from taking effect until the Supreme Court has ruled on them. The primary reason for existence is to allow time-sensitive decisions quick rulings, as it's easier to reach one justice than nine.

From a 2005 news item:

Circuit Justices are responsible for ruling on certain motions arising from their assigned circuits, such as motions for extensions of time. In the case motions for a stay of execution or other motions relating to death penalty matters, the Circuit Justice ordinarily refers the motion to the Court as a whole, but takes the lead in recommending a disposition of the motion.

Similar language describing what they do can be found in other sources.

They are assigned by the Supreme Court itself (I had thought that this was done by the Chief Justice, but I can't find a citation for that). Example order. Usually the circuits are given to a justice who has some background in that circuit. For example, Ruth Bader Ginsburg practiced law in New York City, which is in the second circuit. Of course, not all circuits necessarily have a Supreme Court justice that is naturally associate with that circuit.