A decade ago, with school shootings on the rise across the country, Virginia passed a law requiring all K-12 districts to adopt a violence-prevention method called threat assessment. The method—which relies on trained teams of administrators, counselors, police officers, and others to evaluate and manage alarming behavior—is designed to help avert tragedies like the one last month at Richneck Elementary in Newport News, where a 6-year-old seriously wounded his teacher. But after the law was enacted in 2013, the Newport News district failed for years to use—or even establish—the required threat assessment procedures, according to interviews with three psychologists who previously worked for the district. The psychologists, who asked not to be identified, worked for Newport News Public Schools over the past decade and left for jobs elsewhere prior to the current school year.