Army Maj. Nidal Hasan went on trial in a military court at Fort Hood, Texas, last week with his life on the line.
Hasan killed 13 people and wounded dozens more in a 2009 shooting rampage at the post.
He has admitted that, meaning the Army court martial's purpose amounts to determining whether he should be sentenced to death.
More than a formality may be involved, however.
It already is known that Hasan, a fanatical Muslim and supporter of Islamic terrorists, displayed many warning signs during a very troubled career as an Army psychiatrist.
Yet military authorities did virtually nothing about him until it was too late.
Of course, Army officers in charge of the court martial will not want testimony about that fatal neglect to be heard.
But more needs to be known about it, and perhaps the trial will offer an opportunity for the American people to hear such testimony - and then to ask whether the Pentagon has changed anything.