At times when lexicographer and grammar expert Bryan Garner went before the U.S. Supreme Court on Dec. 8, some justices behaved like supplicants seeking wisdom from him while others showed off their own knowledge to the master.

That’s not the usual dynamic between advocates and justices, but it was an unusual argument because Garner wrote the book—make that several books—about the issues that were before the court in the case Facebook v. Duguid.