[AtlUmpSteve]

Some good thoughts by others. Here's my $.02.

In USA/ASA, it's moot if fair or foul, or IFF vs any routinely caught ball, declared IFF or not, or even when determined (wait and see the exceptions). As long as you judge 1) that was the one fielder that you protect as fielding the batted ball, the runner is out, and as long as you judge 2) it was a routine play on a ball in flight, fair or foul, the batter is also out. The exceptions re: timing would be something like the runner leaving so early as to be called out for leaving early (dead ball out and no pitch, so no batted ball), or so early as to make contact with obstructing F3 while the pitch is still in flight (obstructed runner cannot be put out between those two bases, and the obstruction preceded any interference in that instance).

In NFHS (not repeating the same exceptions, but same), timing is also moot; umpire can judge IFF after the fact, whether declared or not, and no reason not to include during the dead ball that occurs in the interim. So, the issues are 1) is that the fielder you are protecting, and 2) is it an IFF (must be fair in flight at the time of the interference)? NFHS does not include the 2nd out if a foul ball, so R1 is out, and a strike assessed to the batter, in that case.

NCAA result, although wording differently, is the same as NFHS (although the exceptions may differ due to the options available when leaving early). Although the IFF must be declared to be applied, the exception for interference allows for a "potential" IFF to be judged. So batter is also out if fair, batter assessed a strike if foul.