I read a news story the other day. I don't remember the details of who, what, when, where, but I remember the gist of the story. It was a civil case and the plaintiff presented a good case. The defendant's lawyer (respected) demanded that the case be dismissed because there was ample precedent on point, and cited several cases where a court had ruled in the defendant's favor.
The problem came when neither the plaintiff's lawyers nor the judge in the case could find any reference to the cases cited. The respected defendant's lawyer confessed that he had not written the brief himself, but had AI do it. In fact, the cases cited in the brief did not exist. AI made it up.
The respected lawyer groveled before the court. I do not recall the outcome of the case or whether the lawyer was disciplined.