Yeah, courts ruled a lot of things... But the school will try to tell you otherwise, which is why you need to know your shit. You need to know exactally what courts ruled and use it to fight for your rights. Your friend's anti-war posters are something he is allowed to pass out and put on walls, but if they school takes them down, they take them down. The best way to get your opinions out is by passing out papers, not hanging them up, that way they cannot stop you becuase you're not "polluting the walls," or whatever else they might say. The armbands might have been ok at your school, but many schools would flip out. But remember the 1st amendment, and remind your teachers of it.