Fair/Foul down 1B line

[nafxos]

I was the PU for a Junior Legion game tonight and had a 2-man mechanics question come up on a seemingly routine play. Nobody on base and batter pulls a ball down the 1B line. Ball hits in foul territory about halfway to first base and continues past 1B about 1 or 2 feet foul. I raise both arms and call "foul". Before the next pitch, my partner working in A position catches my eye and taps himself in the chest, signalling that was his call, not mine.

I talked to him between innings and said I thought that was my call because it went foul before reaching first. He agreed that the PU has fair/foul responsibiliy "up to" first base, but his reasoning was that since the ball isn't foul until it passes the base, it's his call. I'm in my 2nd year and he was a veteran guy, so I said "fine" and let it go. And it didn't come up again the rest of the game.

Is he correct? If so, it seems the PU should only make fair/foul calls on the first base line with nobody on base if the ball comes to a complete stop before reaching first or a fielder touches it before it reaches first. Everything else would belong to the BU. Is that how people here do it?