WASHINGTON

Shon R. Hopwood was not a particularly sophisticated bank robber.

“We would walk into a bank with firearms, tell people to get down, take the money and run,” he said the other day, recalling five robberies in rural Nebraska in 1997 and 1998 that yielded some $200,000 and more than a decade in federal prison.

Mr. Hopwood spent much of that time in the prison law library, and it turned out he was better at understanding the law than breaking it. He transformed himself into something rare at the top levels of the American bar, and unheard of behind bars: an accomplished Supreme Court practitioner.

He prepared his first petition for certiorari  a request that the Supreme Court hear a case  for a fellow inmate on a prison typewriter in 2002. Since Mr. Hopwood was not a lawyer, the only name on the brief was that of the other prisoner, John Fellers.

The court received 7,209 petitions that year from prisoners and others too poor to pay the filing fee, and it agreed to hear just eight of them. One was Fellers v. United States.