who should call fair or foul?

[JFA67]

Interesting discussion. In my career working HS, ASA and NCAA, the answer is it depends.

This is something to cover in your pregame. if the line isn't marked, the plate umpire has to take it to use the foul pole to judge it.

On the other hand, in three person, it is the base umpire's job in the situation you describe.
That is what I was taught at both ASA national school and the NCAA evaluation tournament I worked several years ago.

If my information is out of date, someone correct me.