KBO's new check-swing challenge system to take effect this week
The logo of the Korea Baseball Organization is seen inside its headquarters in Seoul, July 16, 2021. Korea Times photo by Lee Han-ho
Beginning Tuesday, teams in Korean baseball will be able to ask for video reviews on check-swing calls.
The Korea Baseball Organization (KBO) said the check-swing challenge system will take effect across the league Tuesday, about a month after the league's executive committee, made up of general managers of the 10 clubs, reached the decision to implement the new rule.
The KBO had initially planned to introduce the check-swing challenge at the start of the 2026 season, after testing it out in the Futures League, the KBO's minor league, in 2025. However, several managers have been calling for a prompt implementation of this system, citing the need for accurate and transparent calls.
If the end of the bat crosses a line parallel to the front side of the home plate, it will be ruled a swing. The batting team can only challenge a swing call, and the pitching team can only ask for a review of a no-swing call.
Teams will each have two opportunities to ask for a video review on check-swing calls, and they will be awarded another opportunity in extra innings. If teams are successful in overturning the original call, then they will retain their challenge.
The KBO said its own cameras, not broadcast feeds, will be used for reviews. Bunt attempts cannot be challenged.
Only managers will be allowed to ask for challenges and they must do so within 30 seconds of the call — within 10 seconds if the original call ended an inning or the game. However, if a pitch has already been thrown within those time limits, then managers will not be allowed to ask for a review.
The KBO said it tested the system by reviewing close check-swing calls from recent games and that it expects the new rule to enhance accuracy and transparency on the field.
If video replays do not turn up clear evidence to overturn the original call within three minutes, then the ruling on the field will stand.
If an overturned decision results in a strikeout on an uncaught third strike, then the batter will be ruled out without a tag on him or a throw to first base. According to the KBO, the U.S. minor leagues have the same rule on the dropped third strike.
However, if the ball not caught for a third strike goes out of play, then the batter and all the other runners aboard will each be allowed to take a base.