Catcher's interference is when the catcher illegally hinders the batter from hitting a pitch, usually by the bat making contact with the catcher’s glove. In most cases, the batter is awarded first base, and runners may advance one base if forced.

Quick Scoop

This can happen even if the batter doesn’t fully swing, as long as the catcher interferes with the batter’s attempt to hit the pitch. In MLB rules, the ball is often treated as dead, but the offense can sometimes choose to take the result of the play instead of the interference penalty.

What usually happens

  • Batter gets first base.
  • Any runner forced to advance moves up one base.
  • If a runner is stealing, that runner can also be awarded the stolen base.
  • If the catcher’s interference happens on a steal of home, there can also be a balk penalty.

Simple example

If the catcher’s glove is too far over the plate and the batter’s bat hits it during the swing, the umpire may call catcher's interference. The batter gets first base, and the play may be adjusted depending on whether runners were moving and what result the offense chooses to accept.

Bottom line

It’s basically a defensive penalty: the catcher got in the batter’s way, so the offense gets an advantage.

If you want, I can also explain how catcher's interference differs from obstruction and interference by runners.