The opinion of the court was delivered, by

At common law, amendments of judicial proceedings were discretionary, and not the subject of error, and so it was under some of the earlier Statutes of Amendment: 7 S. & *144R. 177. With us this was changed by the Act of 27th March 1806. By it amendments are allowable of right, subject of course to the legal discretion of the court whether they will or will not “ affect the merits of the cause in controversy.” If they will not, the plaintiff has a right to amend his narr., but not to the extent of introducing a new cause of action, and the defendant his “plea or defence,” either before or on the trial; and the adverse party will be entitled to a postponement of the trial if taken by surprise by such amendment.

A refusal to permit a defendant to alter his plea or defence is undoubtedly the subject of a writ of error : 7 S. & R 177; 11 Id. 98, 126; 13 Id. 248; 3 Penna. Rep. 65; 2 Watts 170; 4 Id. 55; 5 Id. 573; 8 Harris 461; and the decision of the court will be reversed if the proposed amendment reaches the merits of the controversy. As a matter of practice, courts are liberal in receiving amendments without more, generally, than a consideration of what the plea will involve, and the assurance of the counsel that his defence will at best tie in part under it. It is said in Hartman v. Keystone Ins. Co., 9 Harris 466, that inore than this may be asked; and that the party proposing the amendment may be required to accompany it with an affidavit of merits. This would certainly not be necessary if the record itself should show that the proposed change of the plea would affect the legal merits of the case.

In the case in hand, the administrator proposed to amend by adding the plea of non assumpsit to the plea of payment, put in by the intestate. As the record stood, I think it was apparent that the proposed change would greatly affect the merits of the defence. The suit was against the defendant’s intestate, on an irregular endorsement, declared upon in the usual form of a regular endorsement. There was a count also upon a guaranty by the intestate. But the bill of particulars filed by the plaintiff, showed that he rested his claim on the endorsement alone: Shenk v. Robeson, 2 Grant 372; Barto v. Schmeck, 4 Casey 447, and several other cases before, and more than one since, show that on such an endorsement alone, the endorser is not liable to the payee. This being the state of the record, the proposed amendment was very material to the defendant. If allowed, it would put the plaintiff on showing the ground of liability of the intestate, and enable the defendant to meet it. Without it the defendant had no case. Thus it appeared to be and was material, and should have been allowed. I do not appreciate the idea that the statute of amendments makes a difference between negative and affirmative pleas. Both are covered by its terms, and in giving the right to the defendant to amend, subject to the qualification that it is sought to be done on account of the merits, and not for the purpose of gaining some advantage in the manner *145of trying the cause. As^we are of opinion that the amendment should have been allowed, the judgment must be reversed.

Judgment reversed, and venire de novo awarded.