Does it just mean to obtain a ruling in the client’s favor? It can’t just mean that, can it? We wouldn’t say that a lawyer “won” a case if he bribed the judge, or threatened the judge, and got a ruling in his client’s favor that way. I would think we would not say he “won” the case if he simply lied to the judge about the facts, and managed to get away with it. We wouldn’t say a lawyer won a case if a corrupt judge had a predetermined verdict and issued his ruling without any regard to what the lawyers argued. And for the same reason, I don’t think we can say that a lawyer has won a case if he makes a wrong argument, but the judge falls for it, or endorses it for corrupt or otherwise indefensible reasons.
Law is a process of persuasion, and while persuasion may rely on arts like rhetoric, that isn’t the whole of it. Instead, the decision we seek in the legal process is a ruling in the client’s favor for the right reasons, or in the right way. Forcing someone to agree with you, or defrauding them into accepting what you say, or pressuring him into giving in, is not persuasion. And a ruling in the client’s favor for the wrong reasons—simply because the lawyer has fooled the judge, or confused him, or manipulated him for reasons other than the merits of the legal argument—isn’t really a “win,” is it?
If I argue in court “My client didn’t commit the murder because purple monkey dishwasher,” my argument is senseless. It’s not a logical or meaningful statement at all. If the judge rules in my favor anyway—as a personal favor, or because the mayor has secretly ordered him to do so, or because he finds my reference to The Simpsons amusing—then I cannot really be said to have “won” my case in a legal sense. I’ve just managed to secure a ruling in my favor, one which rightly ought to be reversed on appeal. But even if it is not reversed, what I’ve done is to fool the court, not to persuade the court. And in that sense, I have not actually done what lawyers are supposed to do—which is to make an argument that deserves to prevail. “Deserves” meaning, a meritorious argument—an argument that correctly accounts for the facts, or correctly interprets the law, or correctly interprets the Constitution, et cetera.
I have on occasion known lawyers to make bad arguments. Shocking, I know. But sometimes they obtain a ruling in their favor from the judge—and then gloat that the argument can’t have been that bad, after all, since they won! But that does not follow. It would not even follow if the decision is upheld on appeal.
Of course, if one holds—as today’s positivists do—that there are no right answers to legal questions, and that whatever a court says just is the law, then none of what I’ve said is correct. On that premise, there are no such things as frivolous legal arguments (or valid ones), because whatever manages to obtain a verdict in the client’s favor just is ipso facto a win. But if one believes, as I do, that there are right answers to legal questions, correct ways to interpret the law, and a genuine difference between a good and a bad legal argument—that is, if one believes that there is objectivity to the law—then a court decision in the lawyer’s favor is not itself proof that the lawyer’s argument was correct. Instead, the lawyer’s argument is correct only if that argument is actually correct on the merits. (This obtains on whatever criteria for “correct” one uses—textualism, originalism, whatever—except for positivism, for which there is no criteria for “correct” except for the court ruling itself.)