Posterior.
OBR 5.09(b)(1) · OBR 5.09(b)(10)

Running out of the baseline

A runner is out if he goes more than three feet from a direct line to the base to avoid a tag. The catch: the baseline only exists once a fielder tries to tag him — until then, his path is his own.

Key points
  • There is no painted baseline. It is established the moment a tag attempt begins, drawn from the runner's position at that instant.
  • Wide turns, roundabout rundowns, and curved paths to the bag are all legal until a fielder reaches to apply a tag.
  • Running backward toward the previous base to avoid a tag is its own violation — runners can be called out for retreating.
  • Umpire judgment, not reviewable by replay.
In a game

Rundown between first and second, runner veers into the grass as the fielder lunges, and the umpire punches him out.

Ruling · Out of the baseline. Once the tag attempt began, he had three feet of latitude and used more.

Why it moves the scoreboard

Ends rundowns instantly and can kill a rally — and because it is pure judgment, it is one of the most argued calls in the sport.

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