Opinion by

The reasons assigned in support of the demurrer are wholly insufficient.

The remedy at law is neither convenient nor adequate. The bill is first for discovery in aid of a defense to the suit. Under the act of 1798 the appellant might have had a rule to produce at the trial such letters and alleged copies as appellant could specify with reasonable precision beforehand, but the bill avers that she had in fact written no such letters as appellee charged, and the contents of the alleged copies were therefore entirely unknown to her. The effect of deferring the production of such papers until the trial would be to complicate the issue in the suit by a collateral issue on the forgery or genuineness of these letters. Such a double issue could not be tried before the same jury without putting the appellant to the manifest disadvantage of having evidence sprung upon her which she could not by any care prepare in advance to meet. Where there is an issue either direct or collateral on the forgery of papers, it is the constant practice even of courts of law to compel their production for inspection in advance of trial. “ The production of private writings, in which another person has an interest, may be had either by a bill of discovery in proper cases, or in trials at law by a writ of subpoena duces tecum, directed to the person who has them in his possession. The courts of common law may also make, an order for the inspection of writings in the possession of one party to a suit in favor of the other. . . . Such order may also be obtained by the defendant on a special case ; such as, if there is reason to suspect that the document is forged, and the defendant wishes that it may be seen by himself and his witnesses: ” Greenleaf on Evidence, sec. 559; and see Story’s Equity Pleadings, sec. 859. And the fact that they are evi*22deuce for the other side does not prevent. “ If a plaintiff is entitled to the production of a deed or other document as being applicable to his case, his right to such discovery will not be affected by the circumstance that the same document is evidence of the defendant’s case also: ” Bispham on Equity, sec. 561. As a mere bill of discovery therefore the bill is maintainable.

But the bill is for much more than discovery. It is for substantial relief. It charges that the defendant surreptitiously and illegally took from the trunk of appellant’s son, and from appellant’s own bureau, certain letters written by appellant to her son and by her son to her. The letters written by the son to appellant are the latter’s property, and she has a right not only to have them produced but delivered up to her as the true owner. In the letters written by her to her son she has a special property to prevent their publication or communication to other persons, or use for any illegal purpose by the party wrongfully in possession of them. The special right in these letters is one that can only be adequately protected in equity, and the court having acquired jurisdiction for any part of the substantial relief sought will go on and administer full relief as to all the matters in the bill, both the letters and the alleged copies: Bispham’s Eq., 566.

Decree reversed, demurrer overruled, and defendant ordered to answer.