Some courts publish word processing templates for briefs; for example, the U.S. Court of Appeals for the Fourth Circuit: https://www.ca4.uscourts.gov/court-forms-fees/brief-template...

The Eighth Circuit gets really into this, publishing a typography guide for lawyers: https://federalcourt.press/wp-content/uploads/2018/03/Eighth...

Judges, particularly appellate judges, spend a lot of their time reading briefs. So, as you can see, some of them have strong opinions about brief typography. (Judges, as a group, have strong opinions about lots of things).