The Diamondbacks selected Law's contract from Triple-A Reno on Saturday.
Law returned to action at Reno on Aug. 12 and has since given up five hits and no walks while striking out five batters in 6.1 shutout innings. The 35-year-old will now return to the majors for the first time since 2024 to provide extra depth to Arizona's bullpen ahead of its doubleheader against the Giants. Kohl Drake was sent down to Triple-A in a corresponding move.