Interference? Maybe!

[WestMichBlue]

In both cases, it is nothing.

I think that you are wrong, Mike. 8.2.G provides for interference on the B-R regardless of where the ball is located. And the definition of Foul Ball includes a sentence for declaring the ball foul after you have called interference.

There is no play to interfere with if the ball is foul.

The ball was NOT foul; it was live (though over foul territory). It became foul after you called interference, not because it was touched or touched something or stopped rolling.

If you kill the play upon contact,

Why would you kill the play? (Unless you called interference.)

the status of the ball is determined at that moment and it must be foul.

It is not a simultaneous action, it is sequential. (1)The ball is rolling, (2)contact occurs, (3) you call interference and kill the ball, (4) the ball is declared foul because you killed play while the ball (still rolling an untouched) was over foul territory (See Foul Ball definition).

The fair/foul distinction is important IF the B-R is not the one called for interference. If the ball is over foul territory when interference is called then you have a strike on the batter (if they do not already have two strikes). If the ball is over fair territory when interference is called then the batter is sent to 1B.

I just don't understand why a runner on the 3B line committing interference would not be called out the same as a B-R committing the same foul on the 1B side of the field.

WMB