A sham plea is one which is known to the pleader to be false, and is entered for the purpose of delay. There are certain pleas of this kind, which, in consequence of their having been long and frequently used in practice, have obtained toleration from the courts; and, though discouraged, are tacitly allowed; as, for example, the common plea of judgment recovered, that is, that judgment has been already recovered by the plaintiff, for the same cause of action.