The fact that they don't use email makes sense to me, and I say this as someone who works in the field of information technology and who has configured email solutions. The trick about any technology is that it has to have an appropriate use case, and email is designed to allow for near instantaneous long distance communication of messages of varying length of formality to an arbitrary number of recipients at the same fixed cost. Due to its speed however email tends to demand a more immediate response than a traditional memo, and because of this is often less formal.
The Supreme Court when in session has a collection of seven individuals with equal voting power all in the same building, which is filled with clerks and interns. In the past these clerks and interns have relayed communications and it has, in some cases, been considered an honor to do so. As the number of endpoints for a particular communication never exceeds six for any one justice and the communication must be highly formal and proofed traditional email editors are ill suited for this task.
Which brings us to what often shows up for formal emails, i.e. drafting it in a word processor first along with the appropriate letterhead and having it proofread formally to ensure that no mistakes are made. In the SCOTUS' case they simply choose to transmit these using intern-net rather than using their own intranet mail server.
Likewise for those unfamiliar with how decisions are handed down by the court a single justice writes the majority opinion, and other justices can either join the opinion, write a concurring opinion or write a dissenting opinion (other justices can also join in a dissent). Also please remember, that these opinions are not delivered instantly. The court deliberates for several months after hearing the oral argument for a case and having all of the parties file before handing down a decision. So the fact that it takes Justice Kagan's memo an extra ten minutes to reach Justice Ginsberg's is a fairly minor issue given that they will end up talking about the facts of the case at lunch, and both are busy going over prior case law anyways.
The Supreme Court when in session has a collection of seven individuals with equal voting power all in the same building, which is filled with clerks and interns. In the past these clerks and interns have relayed communications and it has, in some cases, been considered an honor to do so. As the number of endpoints for a particular communication never exceeds six for any one justice and the communication must be highly formal and proofed traditional email editors are ill suited for this task.
Which brings us to what often shows up for formal emails, i.e. drafting it in a word processor first along with the appropriate letterhead and having it proofread formally to ensure that no mistakes are made. In the SCOTUS' case they simply choose to transmit these using intern-net rather than using their own intranet mail server.
Likewise for those unfamiliar with how decisions are handed down by the court a single justice writes the majority opinion, and other justices can either join the opinion, write a concurring opinion or write a dissenting opinion (other justices can also join in a dissent). Also please remember, that these opinions are not delivered instantly. The court deliberates for several months after hearing the oral argument for a case and having all of the parties file before handing down a decision. So the fact that it takes Justice Kagan's memo an extra ten minutes to reach Justice Ginsberg's is a fairly minor issue given that they will end up talking about the facts of the case at lunch, and both are busy going over prior case law anyways.