When I started umpiring, this is how determining interference vs. live ball on this type of play was explained to me. Not sure if this is written in any case play or rule book, but it has served me well in deciphering this rule. This includes how to determine whether the ball has "passed an infielder" or not. At all steps below, we are assuming a legally pitched and batted ball was touched by R1 while running the bases at the time the ball was touched:
1) Draw an imaginary line between the two fielders (not including the pitcher) the ball went through. So if the ball was between F3 and F4, you draw the line between them. F5 and F6's location don't matter for this part. Similarly, if the ball is up the middle, you draw the line between F4 and F6, and F3 and F5's location don't matter for this part. Did the ball cross this line before being touched by R1? If yes, then it has passed an infielder, move to step 2. If no, then it has not passed an infielder and R1 has committed interference.
2) After the ball crossed the imaginary line and before the ball was touched by R1, did any other infielder have an opportunity to make a play (that was disrupted by the runner touching the ball)? If yes, then R1 committed interference. If no, move to step 3.
3) Did R1 intentionally touch the ball? If yes, the runner committed interference. If no, then no interference has been committed, it is a live ball, play on.
I'm open to reading what you guys think about this.
