Is potential U.S. Supreme Court nominee Amy Coney Barrett too inexperienced to sit on the nation’s highest court? Barrett’s long career as a law professor in Indiana—but only eight months as a federal appeals judge—has given critics some fodder to argue she doesn’t have the background for a Supreme Court justice.

But what’s the appropriate level of experience for a justice, if any, and how has that experience varied over the decades? A recently updated academic article concludes the current court, led by Chief Justice John Roberts Jr., is historically a “relative outlier” when it comes to the pre-appointment experience of the justices.