But this is in entirely new realms of misunderstanding the Amendment:
An 1885 legal reform known as the Labouchere Amendment had an unforeseen loophole that suddenly made masturbation (as well as fellatio) legal.As if masturbation had previously been legal and as if the law had taken specific cognisance of fellatio before 1885. Variations on penetrative sex between two men had usually been subsumed under 'attempted sodomy' or 'indecent behaviour'. Demands for oral sex within marriage sometimes featured a part of a plea of cruelty in matrimonial cases.
But masturbation, as opposed to indecent exposure, was not illegal. The 'solitary vice' would surely have presented particular difficulties in policing. But, as I argue in Sex, Gender and Social Change in Britain, 1880 to the present it provides a particularly striking example of a sexual behaviour which, though not illegal, was nonetheless highly stigmatised and subjected to other forms of control.