"In determining whether a defendant's mistaken belief disproves criminal intent, the courts have drawn a distinction between mistakes of fact and mistakes of law. (People v. Snyder (1982) 32 Cal.3d 590, 592-593.) While a mistake of fact usually is a defense, a mistake of law usually is not. It is commonly said that ignorance of the law is no excuse. (People v. Cole (2007) 156 Cal.App.4th 452.) 'In the absence of specific language to the contrary, ignorance of a law is not a defense to a charge of its violation.' " (People v. Meneses (2008) 165 Cal.App.4th 1648, 1661.) However, mistake of law can be a valid defense when the crime requires specific intent if the mistake of law negates the intent or other mental state that is an element of the crime. (People v. Cole, supra, 156 Cal.App.4th at p. 483.) For example, in a dispute between a buyer and a seller over title and the right to possess personal property, the buyer's taking of the property under the misconception that he has a legal right to the property is not theft because the intent to steal is lacking. (People v. Photo (1941) 45 Cal.App.2d 345, 353.)