A dance rehearsal in front of the rotunda at the University of Virginia in 2017. (Norm Shafer for The Washington Post)

At the University of Virginia, a software system scans the ether for social media messages that could tip police to a threat of potential violence, enabling campus police to intervene before something happens.

How far the scanning should go, however, should be carefully thought out given the potential for violating the rights and privacy of individuals. Such scanning systems, which comb social media much as the National Security Agency does for coded radio messages from potential enemies, have become fairly widespread.

In Charlottesville, the university agreed to pay $18,500 a year to Social Sentinel, a Burlington, Vt., security company, to use its system to review social media. When key words suggesting an intention for violence surface, the campus police are contacted automatically.

U-Va. began using the system in September just weeks after a “Unite the Right” protest involving Confederate memorials ended on Aug. 11 with one woman fatally rammed by a car driven by a white supremacist. Two state police officers died when their helicopter crashed as they were monitoring the demonstrations.

Speaking to the Roanoke Times, campus police officer Ben Rexrode explained that the university must deal with new realities. “There are so many potential threats and vague sentences being done online. You have to translate the old mentality of ‘see something; say something’ to seeing threats and reporting them and acting on them if necessary.”

The university’s contract with Social Sentinel allows the latter to scan public social media and watch for key words, such as “kill” or “die.” Such words trigger another level of analysis and could eventually send the police very quickly.

Responding to a query in an email, Gary Margolis, the chief executive officer and founder of Social Sentinel, said that the service is not intended to violate privacy rights but uses information publicly available. School districts, universities, colleges, professional sports leagues and convention centers are among its users.

Since going online in Charlottesville in September, the system has led police to intervene in only a few circumstances, some involving incidents of potential self-harm.

The urge to stem violence at schools has gotten renewed attention after a mass shooting on Valentine’s Day at a Florida high school left 17 people, mostly students, dead and more injured.

In the Florida case, there were ample signs that the alleged shooter, 19-year-old Nikolas Cruz, was deeply disturbed and was a threat to others. Following a series of mass shootings, the case has brought pleadings for stricter gun control to higher levels.

One could argue that a U-Va.-style monitoring system might have helped in Florida. But Cruz had long been flagged as a potential threat by school officials, police, social workers and the FBI.

A problem for high school and college students is that they may not understand that what they tap down in brief messages and sent as a tweet or phone message can be regarded as public information. Joking missives can be construed as threats. What young people tweet can be used as evidence in litigation or otherwise held against them.

This tends to dampen the right to privacy and free speech. Unfortunately, technology has brought new threats along with convenience.