AUSTIN, Texas — The Texas Senate has given preliminary approval to barring universities from establishing so-called “free speech zones” which are sometimes used to confine demonstrations to certain areas of campus.

Supporters of the ban say using the free speech zones actually prohibits speech by implying free expression is not allowed across the rest of campus. The measure would still allow colleges to set some regulations to keep demonstrations from disrupting classes.

Free speech zones became common in the 1960s as a way to control campus protests against the Vietnam War. Many colleges dropped the practice decades later, but experts say it has survived at some schools as a way to rein in protests and to regulate outside provocateurs looking for campus soapboxes.

Colorado and Utah this year approved bills banning free-speech zones.