Overview
A checked swing ruling determines whether a batter who attempted to hold back committed to the swing enough to warrant a strike call. The official rules lack a precise definition of a swing; the conventional standard is whether the bat crossed the front plane of home plate, but the call relies heavily on umpire judgment. When the home plate umpire calls a ball, the defensive team may appeal to the base umpire (first or third base), who can overturn the call to a strike. This two-stage process is among baseball's most contentious areas, frequently criticized for inconsistency. MLB has explored objective criteria for checked swings alongside robot umpire discussions, while NPB currently maintains traditional visual judgment by human umpires.