The opinion of the Court was delivered, by
Bell, J.The question here presented falls clearly within the rule ascertained by Heck v. Shener, 4 Ser. & R. 249, Gaw v. Wolcott, 10 Barr 43, and the determinations upon which those cases rest. It is,- that in an action founded on a simple contract, the plea of non assumpsit puts the plaintiff upon proving his whole case, and entitles the defendant, without prior special notice, to give evidence of anything which shows, ex equo et bono, the plaintiff ought not to recover. This is emphatically true of matters of defence springing from or immediately connected with the transaction sued on, and impeaching the consideration of the contract averred by the plaintiff. As he is bound to show everything was fair and honest on his part, his antagonist may rebut the allegation by proving he failed in some point of duty or obligation connected with his undertaking. The usual illustration given of this rule is drawn from the implied promise which the law ascribes to all who, for a valuable consideration, assume the discharge of some professional duty, that it shall be properly and fully performed; and of which Heck v. Shener and Gaw v. Wolcott are instances. If, said Chief Justice Tilghman, in the former of these cases, a physician sues me for his services, I may give evidence that he has treated me unskilfully; or if a carpenter brings suit for work done for me, I may show it was badly done. In the latter case is mentioned Sisson v. Willard, 25 Wend. 373, which rests on the same principle, and is referred to again, only because its general features bear a close resemblance to the case before us. It was assumpsit to recover the price of altering a *133water into a steam-mill, and, under tbe general issue, the defendant was permitted to prove the steam-engine was worthless, without previous notice. The Court said that in an action on a contract, where the plaintiff is bound to show performance on his part, the defendant may, under the general plea, prove non-compliance by the plaintiff, without special notice ; for that which the plaintiff must prove the defendant may disprove. Nor can it make the slightest difference that the undertaking of the former is not by implication, but express, as in this instance. It is true that under our more recent decisions, unliquidated damages for a breach of warranty may be averred as matter of set-off, and then a special plea or notice would be necessary; but, as was justly observed in Saddler v. Slobaugh, 3 Ser. & R. 388, a breach of warranty may, at the option of the defendant, be either reserved as the foundation of a separate action, or set up .as a defence, going to the consideration of the assumpsit sued on. And this is also the doctrine of Shaw v. Badger, 12 Ser. R. 275, where a violation of part of an express contract of sale, originating in non-delivery of a portion of the things purchased, was set up as a defence to an action brought for the residue of the articles sold; under the doctrine of Ileek v. Shener, that when the breach of faith, complained of by the defendant, is parcel of the plaintiff’s ground of action, and touches its consideration, it is, in Pennsylvania, a defence fro tanto, to avoid circuity of action. Indeed, this seems to be admitted by the observation of the Court below, that a defendant “ may set up a failure or want of consideration, because that is good under the issue of non assumpsit, for if there was no consideration, there was not, in law, any assumpsit.” But it was thought the defence was not entitled to be so considered, under the notion that it springs from “ a distinct contract of warranty, made at another time than that sued on.” Literally, it is true the notes in suit were executed at a time subsequent to the warranty the defendant offered to prove. But, in fact, the contract was a unit, agreed upon at the same moment; and though, for the convenience of the parties, the actual execution of -the promissory notes was deferred, they were but the offspring of the original agreement, deriving their sole efficacy from that agreement, as between the original parties. This suit, founded upon them, is, consequently, open to precisely the same defence as though it were brought on the oral contract. The result is, the rejected evidence ought to have been admitted, as furnishing an answer to the plaintiff’s claim, either in whole or part; for as we have seen, it was, in the language of the rule of Court to which we have been referred, u strictly evidence admissible on a general issue plea.”
The error first assigned was properly abandoned; and we do not perceive any mistake in that portion of the charge quoted in the third assignment.
*134But for the improper rejection of the offered testimony, resulting from the erroneous estimate' of its value had it been received, the judgment must be reversed.
Judgment reversed, and a venire de novo awarded.