Casuistry is a process of reasoning that focuses upon specific cases or moral problems, as opposed to a general study of ethical theories. In this broad sense every moral philosopher may be regarded as a casuist in some form. The term also has a narrower meaning as it refers to a group of moralists who, in the 16th and 17th century, systematically adopted this method. Casuistry is now one of the options for those who, in the framework of the post-modern anti-systematic attitude, still feel the importance of serious moral debate and reject easy-minded relativism.
It's a great book on moral philosophy. Although the author does have his own assumptions and focuses his discourse by analyzing and maybe even endorsing the position of the Church of England, he does justice to the depth and breadth of the moral issues encountered and those that have to deal with conscience. At times I got the feeling like he was just jumping carelessly around different "moral traditions" in explicating a certain issue; e.g. Relativism, egoism, utilitarianism, etc.
Reoccuring themes: Moral reality never happens in a vacuum. Authority of conscience. Against settling on vagueness, e.g. making moral decisions based on probability. Loyalty to an institution does not take away the right to conscience of an individual. Against legalism and strict moral laws.