Please don't get me wrong, Justice Perren. I completely agree with you. You're totally right in this one. When a party in a civil action appears pro per, even with a "counsel on the side", there's no disqualification when the opposing party talks directly to the pro per litigant. That's totally permissible. You're also completely correct that a party shouldn't be able to frustrate the other side by making unclear whether they're represented by the "informal" counsel or pro per. Exactly right.
I also don't disagree with what you said when you began the opinion. The first sentence of which says: "Over 140 years ago, our Supreme Court stated, 'A party to an action may appear in his own proper person or by attorney, but he cannot do both.' (Board of Commissioners v. Younger (1865) 29 Cal. 147, 149.)" The Court did indeed say that. And it's generally true, as well as nicely applicable here.
That opening statement caught my eye, however, because, technically, I think it's not, in fact, accurate. In my mind, at least, a party to an action can simultaneously represent himself and be represented by an attorney -- a fact that, if true, disproves at least the universality of the California Supreme Court's categorical statement. When, you might ask, can they do so? When they're an attorney as well. So if, for example, the plaintiff is an attorney, and also formally associates another counsel, in my mind, both (or either) attorney can represent the plaintiff. And hence appear at hearings, enter into stipulations, argue motions, etc. The plaintiff in such a setting is "represented" by two attorneys -- himself (or herself) as well as the outside counsel.
Are there any cases on this precise point? Maybe. Both Scott v. Times-Mirror Co. (1919) 181 Cal. 345 and Conroy v. Waters (1901) 133 Cal. 211 at least come close, as both involved a party to was an attorney and who represented himself (alongside other counsel), and the Supreme Court in each refused to find reversible error notwithstanding the "can't be both pro per and have an attorney" language of Younger.
So I raise the point if only because (1) I hadn't seen the language that Justice Perren quoted ever before (it apparently comes up every couple of decades or so!); (2) it articulates an interesting categorical proposition, and one that even be practically relevant to members of the California Bar; and (3) may be misleading, or even untrue, at the margins.
Not, again, that you're wrong, Justice Perren. I'm with you. Totally. Especially since the plaintiff here was not, in fact, an attorney. Regardless, I just wanted to make a tangential -- and hopefully helpful -- point.