The mass shooting in Lewiston, Maine – the worst in the state’s history – was carried out by a gunman with a known history of mental illness. Maine has what’s known as a yellow flag law. It requires reporting to local law enforcement that a person poses an imminent threat, but it then relies on the police to take the person into custody, order a mental health evaluation and request a court order to have that person’s guns removed. The yellow flag law was not used in Card’s case.