Yes, it was. Look over in the religion forum from 4/14 and there's another story dealing with another such incident. It cite the court decision and how to set the school straight (no pun intended). If it's a public school, unless it can be shown that the shirts were obscene or otherwise created a REAL distraction, they can't stop them. A private school would be another matter.
What happened to the three "R"s at school?
Should a student be allowed to wear a shirt to school that said "The Principal Is A Slut" if he knew that the principal had slept with numerous men?