For example, while a principle-based approach might claim that lying is always morally wrong, the casuist would argue that, depending upon the details of the case, lying might or might not be illegal or unethical. The casuist might conclude that a person is wrong to lie in legal testimony under oath, but might argue that lying actually is the best moral choice if the lie saves a life. (Thomas Sanchez and others thus theorized a doctrine of mental reservation.) For the casuist, the circumstances of a case are essential for evaluating the proper response.
Casuism = Moral relativism, if you read the above block quoted material.
Moral relativism is a strong meme/more of the left.
Looks like more leftist pointy headed professorial stuff to me.