As an emergency room physician, an Army veteran who was deployed to a combat support hospital in Baghdad in 2005, and a biomedical researcher in the field of cardiac-arrest resuscitation, I have been and am, on a daily basis, a witness to grave misfortune. Ordinarily, though, except for medical purposes, I will not discuss what I have seen. Last week a colleague asked me to make an exception. They reminded me that we doctors are at the front lines of the scourge of gun violence, and that to remain silent as this threat to public health continues unabated would be no different than for an oncologist or a cardiologist to stay mum on the dangers of smoking. The doctor's balance between discretion and education is complex. But the news from Newtown, and my colleague's request, convinced me that we have reached the threshold. I can no longer stay silent.