Threat assessment teams formed at many universities to try to prevent violence remain a work in progress, eight years after the Virginia Tech shooting.

The effectiveness and fairness of the teams are also increasingly a matter of debate in higher education.

Supporters of threat assessment teams say they make campuses safer in an age of mass shootings. They include administrators from several departments who meet to discuss individuals of concern and decide how to respond.

Critics say the teams can overreact to individuals who are exercising their free speech rights. In rare cases, the teams have been used to harass whistleblowers and critics of the college administration. Some lawsuits and embarrassing public relations incidents have resulted.

One campus police chief says measuring outcomes is hard because "prevention is invisible."