Anyone who works within and respects the laws in order to achieve evil ends would fall under the heading. Say, the head of a corporation who is exceedingly ruthless, uncaring of suffering caused by his actions, but has excellent legal advice.

For the other approach to Lawful, internal rather than external, someone with a code of conduct which is clearly Lawful but also Evil. For example, someone preoccupied with honour to the point of killing innocents to preserve it. Many Klingons, no doubt, would be Lawful Evil. Many human societies in the past (and some still extant) feature this sort of attitude, too.