What is the standard of care of an attorney who fails to properly perform his duties?

In Lucas v. Hamm, 56 Cal.2d 583, 591, 15 Cal.Rptr. 821, 364 P.2d 685, it was held that an attorney, by accepting employment to render legal services, impliedly agrees to use such skill, prudence, and diligence as lawyers of ordinary skill and capacity commonly possess and he may be liable for damage resulting from failure to do so. This liability may be based on tort or breach of contract, but in either case the liability of an attorney for failure to properly perform his duties is governed by the general standard of care described in Lucas, supra. (See Lucas v. Hamm, supra.)