California Penal Code Section 17(b)
(b) When a crime is punishable, in the discretion of the court, either by imprisonment in the state prison or imprisonment in a county jail under the provisions of subdivision (h) of Section 1170, or by fine or imprisonment in the county jail, it is a misdemeanor for all purposes under the following circumstances:
(1) After a judgment imposing a punishment other than imprisonment in the state prison or imprisonment in a county jail under the provisions of subdivision (h) of Section 1170.
(2) When the court, upon committing the defendant to the Division of Juvenile Justice, designates the offense to be a misdemeanor.
(3) When the court grants probation to a defendant without imposition of sentence and at the time of granting probation, or on application of the defendant or probation officer thereafter, the court declares the offense to be a misdemeanor.
(4) When the prosecuting attorney files in a court having jurisdiction over misdemeanor offenses a complaint specifying that the offense is a misdemeanor, unless the defendant at the time of his or her arraignment or plea objects to the offense being made a misdemeanor, in which event the complaint shall be amended to charge the felony and the case shall proceed on the felony complaint.
(5) When, at or before the preliminary examination or prior to filing an order pursuant to Section 872, the magistrate determines that the offense is a misdemeanor, in which event the case shall proceed as if the defendant had been arraigned on a misdemeanor complaint.
eff. Oct. 1, 2011.