How have the courts interpreted mistake of fact and mistake of law?

Roland agrees the jury was properly instructed regarding mistake of fact and mistake of law but contends the jury must not have followed the instructions. With respect to mistake of fact, the jury was instructed, in part: "The defendant is not guilty of Penal Code section 487 (Grand Theft) if he did not have the intent or mental state required to commit the crime because he did not know a fact or mistakenly believed in good faith a fact." (CALCRIM No. 3406.) Regarding mistake of law, the jury was instructed: "It is not a defense to the crime of Penal Code [section] 115 (Filing a False Document) that the defendant did not know he was breaking the law or that he believed his act was lawful." (CALCRIM No. 3407.) We presume the jury followed these instructions. (People v. Martinez (2010) 47 Cal.4th 911, 957.) Other than mere conjecture, Roland offers no reason to abandon this presumption. Based on the record, the jury reasonably rejected Roland's claim that he was acting under the mistaken belief that his actions were entirely lawful.

We thus reject Roland's contentions and conclude substantial evidence supports Roland's four convictions for grand theft by false pretense.