As the U.S. Supreme Court's docket has steadily shrunk over the decades, the number of amicus briefs filed in the court has exploded. 

"I think fewer cases means more concentrated attention on the cases that are up there," said Anthony Franze, a Supreme Court lawyer at Arnold & Porter who has studied amicus filings in the high court for more than a decade. "It's no longer really jaw dropping to see a case that has more than 100 amicus briefs in it."