¶1delivered the opinion of the court.
¶2Berry could not be made subject to a law passed subsequently to his undertaking as a prosecutor, which changed that undertaking to his prejudice. At the time the defendant became the prosecutor, the statute provided (R. C. 1845, p. 249, sec. 10,) that, “ if upon the trial of an indictment, whereon the name of a prosecutor is endorsed as such, according to law, the jury shall acquit the defendant, they shall determine and return, together with their verdict, whether the prosecutor or the county shall pay the costs, and the court shall render judgment accordingly.” Afterwards, and before the last trial of the indictment, the foregoing provision was so amended as to provide that if the jury fail to declare by whom the costs shall be paid, the court shall render judgment against the prosecutor for the costs. (R. C. 1855, p. 451, sec. 11.)
¶3It is obvious that the undertaking of the defendant must be controlled by the statute in force when a liability to it was *357incurred. By that statute, in the event of the contingency which has happened, the prosecutor was not liable for the costs. As he was only liable when the jury who tried the indictment determined that he should pay them, and as the jury failed to declare in their verdict whether he should pay or not, it is obvious that no judgment could be rendered against him for the costs. It was not competent for the legislature to make him liable on the happening of an event not contemplated in his undertaking. The court therefore erred in making the act of 1855 applicable to cases in which persons had become prosecutors under the act of 1845.
¶4the judgment will be reversed;