Interference @ Plate ?

[bd41flpk]

Can someone please state clearly as well as reference a rule as to when on a play at the plate between the catcher and a runner is considered 'interference' vs. 'obstruction' vs. 'incidental contact - (as they say in socer) play on'

(1) Runner coming around to score is heading towards home and of course is not looking back at the ball. The throw is up the line and the catcher runs up the line to catch the ball and runs into the runner. Result: Runner is knocked off his path......

Ruling: Obstruction ?

(2) Same play, ball gets to the catcher a split second prior to the runner and the runner runs into the catcher.....Result: catcher drops ball; runner scores

Ruling: Interference ?

(3) Same play, ball and runner get to the catcher @ approximately the same time and there is a collision (catcher is in the proper position on/in front of the plat)....Result: catcher drops ball; runner scores

Ruling: Incidental contact; play continues.

Please direct me to the ASA rule(s) that apply?

Thanks