Cal. Civ. Proc. Code § 340.6
(a) An action against an attorney for a wrongful act or omission, other than for actual fraud, arising in the performance of professional services shall be commenced within one year after the plaintiff discovers, or through the use of reasonable diligence should have discovered, the facts constituting the wrongful act or omission, or four years from the date of the wrongful act or omission, whichever occurs first. If the plaintiff is required to establish the plaintiff’s factual innocence for an underlying criminal charge as an element of the plaintiff’s claim, the action shall be commenced within two years after the plaintiff achieves postconviction exoneration in the form of a final judicial disposition of the criminal case. Except for a claim for which the plaintiff is required to establish the plaintiff’s factual innocence, the time for commencement of legal action shall not exceed four years except that the period shall be tolled during the time that any of the following exist: