Just when you think Americans have come up with all the possible excuses to relieve themselves of any possible guilt from any action they do, someone comes up with a new one.
There are just SO many things wrong with this… the first, and probably most important, is that the entire concept of law is based on the assumption that people are free agents, at least to a limited degree (this has been undermined more and more as of late with things like insanity pleas for cases in which the defendant had no real history of mental disturbances) and therefore are responsible for their own actions. Claiming that something that happened to your ancestors almost 150 years ago caused you to commit a crime today completely goes against that. Saying that you were impacted by something that happened to YOU is one thing, and understandable (although in all but the most severe cases the individual should be assumed to be able to overcome circumstances and make decisions for themselves) but something that happened to ancestors sevenor more generations back is just stupid. The article does say later on that the lawyer's job is to try every possible defense, and so it's possibly worth a try if there is absolutely NO other way to defend what your client did, but it should definitely not pass muster with the judge.
In today's victim society, however, that's by no means a guaranteed thing.