In 1819.
Ok, so that's not exactly SoCal appellate news. But readers are no doubt interested in all facets of "appeals," even historical ones. And what probably is news to most readers is an antiquated use of the term "appeal." We'll let the great Charles Rembar explain (from his book The Law of the Land: The Evolution of Our Legal System, ch. 2 "Battle"):
"The word 'appeal' has had two meanings in the law. There is the one today familiar: review by a higher court of the judgment of a lower. The other is strange now even to attorneys: it was the name of a criminal proceeding brought not by government but by a private citizen. Its roots went deep in English history. For long years before there was prosecution by the state, there was prosecution by the person wronged (or, in case of homicide, his next of kin). The trial of crime had to wait upon the suit of individuals. There was no governmental accusation, no official pressing of the case, no district attorney or king's counsel. Near the end of the twelfth century, public prosecution came into being: indictment by the sworn testimony of neighbors, under the goad of royal justice. But the private suit for crime did not die out. Appeal and indictment existed side by side."
Rembar details the fascinating case of Ashford v. Thornton, which was the impetus for the Lord Chancellor to introduce the bill to abolish private appeals following acquittals. (The wikipedia entry is almost as good as Rembar's version, though not nearly as eloquent.)