Jon Wiener teaches US history at UC Irvine.

A May Day warning has been issued to the ten-campus University of California system by office of the president, Mark G. Yudoff: “Avoid all protests.”

This warning came in an e-mail, sent to all campuses, issued by Connexxus, the university’s travel management program, headed “Travel Alert—Protests across US Tuesday May 1st.”

“Various activist groups will stage protests, rallies, and marches across the US on May 1,” the president’s office reported. “The Occupy Wall Street movement has called for a general strike, asking participants to abstain from work and economic activity on the same date.”

The message, apparently sent to all students, faculty and staff, was addressed to “anyone” traveling to cities where demonstrations had been planned. Under “Impact,” the message declared, “Transport, business disruptions; possible scuffles with police.” The advice for May 1: “Allow additional time for ground transportation near protest sites.  Avoid all demonstrations as a precaution.”...