What if a lawyer lets his teenage daughter write the brief he submits? Is she legally liable? Of course not. He’s the one who filed it.
Or if he copies a brief from a textbook, do you sue the publisher or the original author? Of course not.
Responsibility follows the actor with agency and accountability. Same with AI. The lawyer who files the brief is the one held liable.
So I guess AI isn’t going to replace all those humans after all — right?