Executing kids under 18 for their crimes is no longer permitted -- and rightly so.

This is a line that plainly needs to be drawn though knowing exactly where it goes can be difficult. Eighteen was chosen from one of several traditional "ages of accountablity." Thirteen and 16 seem a bit too early to draw the line; 21 is too old.

Justice O'Connor dissented, pointing out that there are obviously pathological monsters younger than 18.

However that may be, there are quite enough other true monsters that can't receive capital punishment soon enough.