Bases loaded. one out. Batter hits a fly to center that's caught. Runner on 2nd takes off as soon as the ball is hit. The runner of 3rd scores after the catch is made. After the runner scores, the ball is thrown to 2nd to appeal the runner not tagging. A double play is called. Where is the rule that says the run from third counts? Thanks.

larry s .. in your scenario the run would score because the appeal happened after the runner scored.. look at B2


5.7 • SCORING OF RUNS
A. One run shall be scored each time a runner crosses the scoring line or touches the scoring plate, after legally touching all bases in proper order.
B. No run shall be scored if the third out of the inning is the result of:
1. A batter-runner being called out prior to reaching first base or any other runner forced out due to the batter becoming a batter-runner.
2. A runner being put out by a tag or live ball appeal play prior to the lead runner crossing the scoring line or touching the scoring plate.
3. A preceding runner is declared out on appeal involving a force play. NOTE: An appeal may be made after the third out in order to nullify a run.
C. A limit of five runs per inning, except in the “open inning,” may be scored until the final inning. (See §5.5(1) for Major-Plus exception).

one other thing as far as making an appeal.. the appeal can't be made while the ball is still in the outfield.. I once had a 2b man yell out blue the runner on 2nd left early just as the outfielder was throwing the ball back in to the infield and before the runner on 3rd had scored.. I tried to explain to him that the ball must be back in the infield and then a proper appeal can be made