The word for this month is RES JUDICATA. According to Black's Law Dictionary, Res Judicata is Latin for "a thing adjudicated" and is an affirmative defense barring the same parties from litigating a second lawsuit on the same claim, or any other clam arising from the same transaction or series of transactions and that could have been - but was not - raised in the first suit. The essential elements of Res Judicata are:
So, for example, say Dick and Jane contract with Bob to build them a house - who held himself out to be a contractor (but was not). Say Bob takes the money, skips town, and does not build the house. Dick and Jane sue Bob for Breach of Contract and get a judgement against Bob. Later, Dick and Jane find out they could have also sued Bob for Fraud and try to re-file another action against Bob. The Fraud action would be an barred under the doctrine of res judicata because Dick and Jane could have brought the action for Fraud against Bob in the first case, but didn't. For further discussion on contracts and res judicata, might I suggest you look at American Jurisprudence, 2d (West).
Another one? Say you are looking to get divorced from your wife. Say, wife just had a kid and you're saying it's not yours. Say judge orders a paternity test. Say the paternity test comes back and says the kid is really not yours and the judge enters a final decision as to the true paternity of the child. Later, ex-wife tries to demand child support for that child. Her claim may be barred under the doctrine of res judicata because the issue of paternity had already been decided by the paternity test/final decree. I say may because some states don't care what a paternity test says - they just want someone to take care of the kid. So, look to the laws of your jurisdiction to find out how the law applies to you. You may also want to take a look at the American Law Reports, 2d (West) and look in the index under res judicata and paternity.
One more? Say Dick (defendant) was sued for negligence by Paul (plaintiff). Say Dick lost and had to pay court costs and fees to the Paul. Say Jane (Dick's wife) later sues Paul the plaintiff to recover costs lost from their community (i.e. the community of the Dick and Jane marriage). Because Jane is married to Dick, Jane's claim may be barred under the doctrine of res judicata because Jane would be a party in privity with Dick. For more information on res judicata in negligence actions, take a look at Proof of Facts 2d (West).
Fact is, there are a whole bunch of resources that deal with res judicata as well as tons more legal concepts that you've probably never even dreamed of - all waiting to be discovered at your local county law library.