Martese Johnson. (Andrew Shurtleff/Associated Press)

WE DON’T KNOW the sequence of events that ended with the bloodied face, captured on video, of Martese Johnson, a 20-year-old African American junior at the University of Virginia who required 10 stitches after he was tackled and arrested by agents of the state’s Department of Alcoholic Beverage Control , who were white. We don’t know if he was drunk or swore or somehow obstructed justice after he was carded and refused entry to a bar adjacent to the school, as the misdemeanor charges against him allege. Mr. Johnson maintains he did nothing wrong.

We do know this: If officers treated every underage black college student who had a few drinks or mouthed off to authority figures or got carded at a bar as they did Mr. Johnson, campuses across the country would be blood-spattered cauldrons of racial hostility and the courts would be clogged with undergraduates.

Whatever happened on the early morning of March 18 with Mr. Martese and the ABC agents who arrested him, it’s a fair bet that better policing would have produced a better outcome. That’s the sound logic behind Gov. Terry McAuliffe’s swift action last week, ordering that ABC agents be retrained and reining in the agency’s law-enforcement arm. From now on, agents operating in college communities will get with a program set by local police departments and the colleges themselves.

As U-Va. President Teresa A. Sullivan put it, “Getting arrested shouldn’t involve getting stitches.”

The Democratic governor’s order recognizes that ABC officers — a corps of just 130 special agents invested with police powers to enforce liquor laws in bars and restaurants, as well as to prevent underage drinking — probably are not well-prepared to deal with college students.

Handling college students — tipsy, rowdy, insolent or falling-down drunk — is in the institutional DNA of local cops in college towns like Charlottesville, Richmond and Blacksburg. For ABC agents, it’s a sideline, albeit one they’ve been asked to focus on increasingly as campus drinking has become a focus of concern.

The incident with Mr. Johnson, one of just five students from the College of Arts and Sciences elected to U-Va.’s prestigious Honor Committee, is not the first unhappy outcome involving ABC agents and a student. Two years ago, six plainclothes ABC agents, one with gun drawn, collared an undergraduate in Charlottesville as she was pulling away from a parking lot. The agents thought the student had a case of beer; in fact it was sparkling water.

That mishap resulted in a lawsuit against ABC by the student, which was settled for more than $200,000 — a rather expensive resolution given the circumstances from which it arose.

Universities are right to crack down on undergraduate drinking, which gives rise to sexual violence, among other serious problems. It’s fair to ask ABC to help, for example by making sure liquor stores and restaurants get the message that they shouldn’t serve underage students. It’s equally important that ABC agents get the message that restraint and measured responses are critical to good policing.