ah, but lawful is not the operative word here. Lawful EVIL people use the instituions of law to best benefit themselves, i.e. all lawyers are therefore lawful evil
Anyway, its interesting to note the actions of Drows. Are they truely evil? I mean, in a way there lifestyle is tough, but they are loyal to their societies parameters. For example, In Yemen if you import pork it means instant death, but in Ireland no one gives a second thought to eatng tasty pork sausages. Both would view each other predelictions as being barbaric, but those within their respective would see such behaviour as normal, even righteous. Could not the same argument be extended to drow?