Can't go out for lunch in PA?

[hotpod]

My wife's employer gives the staff a half-hour break, unpaid, for lunch each day. Recently the boss has stopped allowing people to leave the building during their lunch break; they're required to stay in the building.

Is this legally enforceable, if employees are off the clock for their break?

Thanks.

[cbg]

Funny, but I just read an article about this in an HR journal a week or so ago. You can be required to stay on the premises; if you are subject to being called back to work, you have to be paid for the time; if you are not subject to being called back to work, you don't have to be paid for the time.