In 2014-09, the British decided to ban quite a large number of sexual acts in pornographic films including: female ejaculation, spanking and face-sitting, all without any justification explaining the need for the measures. Presumably, there is some prude in power who finds these particular acts disgusting, who imagines he is the honourary mother of all Britons and who thinks His god put him in charge of British pornography.
I can’t think of any argument for banning harmless acts. Of course, you could at least make a case for banning harmful ones, e.g. bareback sex, needle sharing, extreme stretching leading to an emergency room visit afterwards, rape, use of firearms, simulated snuff, overeating or smoking on the grounds emulating the actors might harm someone.
Even when there is a clear harm from viewing something, or emulating it, you have to think twice about banning it. With fantasy life blocked, the porn aficionado with a smoking fetish, for example, will turn to real life or black market porn sources. As Napoléon observed One should never forbid what one lacks the power to prevent.
Further, you would also have to build a case for banning some activity in porn films, such as simulated snuff, but not in family-rated films.~ Roedy (1948-02-04 age:69)