I wasn't thinking of denying bathroom privileges. I mean, every classroom I've ever been in has had a door that functions like most doors do: when locked, it can still be opened from the inside. The door might need to be relocked after people leave - or if there's a deadbolt, someone will need to turn the little knob again. People have to knock to get back in. Easy-peasy.
My husband's school is currently on high alert. It's one of about four local schools who have had threats or rumors of a possible school shooting since the Sandy Hook tragedy. It's probably not serious, but the school isn't taking any chances. Every teacher is keeping his or her door locked during the day and there's increased police presence - increased because it's normal, here, to have cops in the hallways.
To answer an earlier question about why cops are usually in schools, these are the reasons I've heard:
* It deters things like fighting in the halls - those cops will treat it just like they'd treat a fight on the street, and kids will end up in cuffs, possibly even get a ride in the squad car.
* It gives teachers an authority figure to call on beyond the principle. When a student starts acting ready to swing on a teacher, in the past, all they could do was ring the principle. Now, they can ring an actual cop, which most students find far more intimidating... and who, at any rate, is better trained and prepared to deal with sudden violence than a high school principle.
* It makes students think twice about bringing drugs to school, distributing them or using them on campus. Especially when the cops are known to occasionally bring drug dogs and stroll by the lockers or visit classrooms.
* On the other hand, the cops chosen for this duty generally like children, and are friendly. The drug dogs chosen for this duty are the sort that are also taken to county fairs and to do talks and whatnot, and are safe to pet. So the kids get used to having a cop around, to talking to him, to smiling at the local drug dog and occasionally getting to scratch him behind the ears. The cop is an authority figure, yes, and can haul your butt off to jail if you take a swing at someone or bring drugs to school, but he's also someone you see all the time, who makes sure no one can take a swing at you, and who you can talk to.
* Having a cop at school also tends to make parents feel better, especially when compared to some of the alternatives: things like metal detectors and guard shacks and high fences with razor wire across the top (these are all examples from my home town and surrounding area.)