In Virginia v. Stewart, Chief Justice Roberts tries to draw the distinction between a private litigant suing a public litigant, with an agency of a state suing the state, by comparing, eating and cannibalism, and murder and patricide:

It is the difference between eating and cannibal- ism; between murder and patricide. While the ultimate results may be the same—a full stomach and a dead body—it is the means of getting there that attracts notice. I would think it more an affront to someone’s dignity to be sued by a brother than to be sued by a stranger. While neither may be welcomed, that does not mean they would be equally received