How about Neutral Evil? Yes, she claims to have morals and codes, but the plot then makes a point of having her conveniently run roughshod over them. She's not completely Chaotic, since she still has inhibitions*, but "lawful" is an extremely loose term in the Anitaverse. All things considered, d'you think she's a Blackguard? (http://www.d20srd.org/srd/prestigeClasses/blackguard.htm)

*(said inhibitions changing every few seconds and/or as the plot demands them)