I've read that (U.S.) law is basically contradictory: you can start with generally accepted legal principles and derive both a conclusion and its negation.
I suspect that computers are going to have a hard time dealing with this. ;)
Law students are certainly sometimes called to argue both sides of an ambiguous question, and litigators have to argue on behalf of their clients. Furthermore, the big, famous cases in America are almost always Supreme Court cases. But any case that makes it to the Supreme Court has survived intense selection pressure. The overwhelming number of cases that are actually litigated are resolved in the lower courts. A greater number of potential cases are settled or resolved before trial. The law is mostly confusing only at at the very distant margins.
I...
http://www.nytimes.com/2011/03/05/science/05legal.html?pagewanted=1&ref=general&src=me