Can an attorney be disciplined for "mere ignorance of the law"?

This court has long recognized the problems inherent in using disciplinary proceedings to punish attorneys for negligence, mistakes in judgment, or lack of experience or legal knowledge. (See, e. g., Call v. State Bar (1955) 45 Cal.2d 104, 110-111, 287 P.2d 761; Friday v. State Bar (1943) 23 Cal.2d 501, 505-508, 144 P.2d 564.) In Friday,[28 Cal.3d 689] however, much of the court's expressed concern dealt with the absence of any statute or disciplinary rule permitting the imposition of discipline for "mere ignorance of the law." (Id., at p. 505, 144 P.2d 564.) In the case at bar, such authorization is present in the form of rule 6-101.