¶1The evidence given by the plaintiff in this case that he was, in the various cases put hypothetically to his witnesses, entitled to his commissions, was improper and inadmissible. Whether upon a state of facts proved he was entitled to commissions or not, is a question of law, and the opinion of witnesses thereon is not competent.
¶2If the testimony can be regarded as amounting simply to proof of a usage of brokers and dealers in the city to charge and pay commissions in such cases, it is still objectionable. First, because the proof, if it established any agreement between the plaintiff and defendant, showed an express contract, which, not being in any respect vague or uncertain in its meaning, could not be altered or affected by any proof of such usage ; and second, because there is no evidence that the plaintiff is a broker or commission merchant at all, and therefore the usage is not shown to apply to him.
¶3We are not disposed to decide whether upon the other evidence, laying out of view the objectionable testimony, the plaintiff would be entitled to recover. It is only in a very clear case, and one in which we feel assured that we can do complete justice between the parties, that we will disregard an error of this description. And we cannot say that here the court below may not have been influenced by the illegal testimony.
¶4The judgment must be reversed; and as we have no discretion on the subject of costs, they follow of course by the statute.
¶5Judgment reversed.