D. Aikenhead Stroud, Fortune-Telling and Mens Rea, 37 L. Q. Rev. 488 (1921)
Stroud's article addresses what I think is a crucial issue when it comes to regulating fortune-telling and other paranormal or religious practices (such as faith healing, dowsing, cleansing a house of evil spirits, etc.) that involve the exchange of payment for a service in which there is the potential for fraud. That issue is whether the good faith of the practitioner is relevant; that is, if the psychic medium, fortune teller, exorcist, faith healer, etc., sincerely believes they have a supernatural power and are exercising it to the best of their ability, should this be a defence to a charge under the variety of statutes that have been used to prosecute such individuals in the past?
Stroud's article discusses a then-recent case that squarely addressed the question in the context of the English Vagrancy Act of 1824, which was the law often applied in this context. The case, Stonehouse v. Masson,  37 T.L.R. 621, stands for the proposition that the good faith belief of the defendant is irrelevant to a charge of "pretending or professing to tell fortunes" under the Act. Stroud states that "[t]he real ground of decision was expressed by Darling J., who said he had 'come to the conclusion that the Legislature has decided that fortune-telling and professing to tell fortunes was a fraud, and that it was a deception in itself, and that quite independently of the question whether the person who told the fortune believed that that she could tell fortunes or not.'" (p. 488-89)
Thus, Stroud (and the Court in Stonehouse) argue that the mens rea requirement of a statutory crime is only to intentionally do that which is forbidden by the statute. They thus distinguish general mens rea from the concept of specific intent, and Stroud concludes "[w]hat the law prohibits is any profession of occult powers of divination, whether sincere or insincere, and the requirement of mens rea is satisfied by an intentional infringement of that prohibition, without any fraudulent or deceitful intention." (p. 488-89)
This is an old article discussing an old case in the context of a very particular old statute. Nonetheless, it ties in nicely to the article I'm currently writing on whether criminal bans on witchcraft and fortune-telling comport with modern freedom of religion guarantees.