Robot umpires are coming to MLB. Here’s how they work

NEW YORK (AP) — Robot umpires are coming to the big leagues this year. The Automated Ball/Strike System will be introduced in the form of a challenge system in which the human umpire makes each call, which can be appealed to the computer . Robot umpires have been tested in the minor leagues since 2019, with recent testing done at Triple-A since 2022, MLB spring training last year and at the 2025 All-Star Game in Atlanta.

Here's what to know about MLB's robot umps. How does the Automated Ball-Strike System work? Stadiums are outfitted with cameras that track each pitch and judge whether it crossed home plate within the strike zone.

In early testing, umpires wore ear buds and would hear “ball” or “strike,” then relay that to players and fans with traditional hand signals. The challenge system adds a wrinkle. Human umps call every pitch, but each team has the ability to challenge two calls per game.

Teams that waste their challenges get one additional challenge in each extra inning. A team retains its challenge if successful, similar to the regulations for big league teams with video reviews, which were first used for home run calls in August 2008 and widely expanded to many calls for the 2014 season . Only a batter, pitcher or catcher may challenge a call, signaling with the tap of a helmet or cap; and assistance from the dugout is not allowed.