 It is based on the principle that rather than studying highly abstract summaries of legal rules (the technique used in most countries), the best way to learn American law is to read the actual judicial opinions which become the law under the rule of "stare decisis" (due to its Anglo-American common law origin).To set up the case method of law study, American law professors traditionally collect the most illustrative cases concerning a particular area of the law in special textbooks called casebooks.Some professors heavily edit cases down to the most important paragraphs, while deleting nearly all citations and paraphrasing everything else; a few present all cases in full, and most others are in between.