delivered the opinion- of the court.

This was an action of assumpsit, broúght by the plaintiff in error against the defendant and four others, upon a note for eight thousand dollars, payable twenty-four months after date, with' interest at eight per cent, per annum after twelve months. During the pendency of the suit the defendant obtained an order of the court, permitting him to sever in his defence, from the other parties, and allowing him a separate -trial. He pleaded several pleas, alLof which were sworn to, amongst others, that the note after its execution had been materially altered without his consent, by inserting the words “with interest at eight per cent, per annum after twelve months.” No. exceptions were filed, to the order of ’severance.

Upon the trial,-J. B. Fox, one of the defendants, who had pleaded similar pleas, was called as a witness by the defendant Lum, was objected to by the plaintiff, but permitted to testify by the court. *419To this exceptions were filed. Instructions to the jury were asked by both parties. Those of the plaintiff were refused, and those of the defendant given; to which, exceptions were likewise' filed by the plaintiff. There was a verdict and judgment for the defendant, a motion for a new trial, which was overruled, and the case brought by writ of error to this court.

As there was no exception taken to the order of severance, we cannot make it the ground of reversal; we shall therefore pass it over with the single rerpark, that we are not satisfied’ of its correctness, and we do this merely that wé may not seem to give it sanction by oür silence. See 3 Phil. 135; 4 Bibb, 207.

The effect of this order of severance upon the liability of the parties to the costs of the suit, may. claim a moments attention. The .witness was certainly liable to a partial, if not to an entire extent for the costs, in' the event of recovery by the plaintiff. He was not released, nor indemnified in any way for this liability, and we think this was sufficient in point of interest to exclude him. 1 Phil. Ev. Cowen’s ed. 61; 2 ditto 137; 3 do. 1563, et seq.

We proceed to consider the propriety of admitting Fox as a witness, upon .other- grounds. The rule which excludes a party to a suit from testifying under all circumstances is one of policy, and has undergone occasional relaxation. See 3 Phil. 135, 136. How far that relaxation is proper, we shall not now inquire; but shall confine ourselves to the objection growing out of his being a party to the instrument. He was» a joint maker of the note, and was permitted to testify in behalf of another maker, without a release. A. joint debtor not sued is often received as a witness. When called by the plaintiff he is competent, because his interest is adverse to the plaintiff, 2 Phil. 81, 82, unless he is called to prove a joint liability. When called by' the defendant and released or otherwise discharged of his interest, he is equally competent. 3 Phil. 1520, 1521. Some cases hold that he is competent without a release, as being interested against the defendant, or as having an interest either way; but a majority of the cases hold that he is not competent without a release, because he is interested to defeat the recovery, and thus save his liability to contribute for the costs of the suit in'which he is a witness, as well as *420for the debt. 3 Phil. 1521; 8 Vermont Reports, 401. We believe that the release is necessary.

In this case, moreover, where the witness was an original party to the suit, had full notice of it, and an opportunity to defend it, the record would be evidence against him, in an action for contribution, if the verdict had been for the plaintiff. 2 Stark. Ev. 195. He would thus be brought under the operation of the rule, “that a witness is not competent, if the verdict can be used in evidence agains,t him, in case-the party for whom he is called should fail in the action.” 1 Phil. 55. The judgment must therefore be reversed for the admission of an incompetent witness.

In the various instructions asked for on both sides, there seems to be but a single point, which it is necessary for this court to notice. Was it incumbent on the -plaintiff or the defendant to account for the alteration of the note. Whether the alteration was made before or after its execution and delivery, is a question of fact; to be determined by the. jury, by all the testimony taken together. In the absence of evidence which will satisfy their minds, certain’ legal presumptions may be called in to their aid. The general presumption is. in favor of the fairness of all transactions, and against the imputation of fraud. But negotiable paper seems to form an exception to this rule, and if the instrument appear upon its face to have been altered, it is for the holder to prove, and not for the defendant to disprove, that it was altered under circumstances which will make it still available. Chitty on Bills, 212; Henman v. Dickinson, 5 Bing. 184; 15 Com. Law Rep. 409.

Judgment reversed.