Nagisa Oshima's 1976 study of erotic obsession had already caused difficulties in the US (where the print was seized by Customs) and Japan (where the book of the film was prosecuted for obscenity), before it arrived in the UK. The film was first shown here at the 1976 London Film Festival, where it won the critic's prize, before being acquired by the Gate Cinema in Notting Hill. At the time, the BBFC's Secretary, James Ferman, expressed the informal view that the film would require very heavy cuts to its more explicit sexual details before it could be awarded an X certificate for national distribution. Any such cuts were likely to be very damaging to what was already a critically acclaimed film, from an established director.

Ferman therefore suggested that it would be preferable to show the film, without cuts, to members of private 'cinema clubs' rather than approach the BBFC for a formal classification decision. Nonetheless, Ferman suggested that the film should not be opened, even under 'club' conditions, until after the Obscene Publications Act (OPA) had been extended to include films (by the Criminal Law Act in 1977).  This, he believed, would allow the film to benefit from the requirement in the OPA that publications must be judged 'as a whole' and that a defence of artistic merit was permitted. Under the test of common law indecency, which currently applied to films, it was likely that the film would be vulnerable to prosecution because any number of explicit scenes could be viewed out of context and prosecuted. Even then, one scene was edited before the film finally opened at the Gate Cinema Club in 1978, as a result of further legal advice. The cut was to remove a scene in which an adult woman tugs a young boy's penis, which might constitute an 'indecent' image of a child under the terms of the newly introduced Protection of Children Act 1978. In this slightly censored version, the film continued to be shown for a number of years, without a BBFC certificate, in cinema clubs.

In 1982 the film was released on video by Virgin Video, without a BBFC certificate. However, this release was removed from the shelves after the Video Recordings Act 1984 made classification of videos in the UK mandatory. It was not until 1989 that the film was officially submitted to the BBFC, this time by the British Film Institute, for a limited cinema re-release.

Even in 1989, the film contained scenes of real sex that went beyond what the BBFC would normally be prepared to classify for general release. The BBFC therefore sought the legal opinion of a top QC as to whether the film was likely to be considered obscene under the terms of the OPA and whether the scene that had previously been censored for club screenings was indeed likely to be legally 'indecent' under the terms of the Protection of Children Act. The QC's advice was clear on the issue of obscenity and confirmed Ferman's own opinion in 1977. The OPA required that, in assessing whether or not a film was obscene, the film had to be considered 'as a whole'. It was not sufficient to examine one scene in isolation but, rather, the overall purpose and effect of the work must be taken into account. Furthermore, the Act permitted a defence of artistic merit, which could allow material that would not normally be considered acceptable to be published if it was in the 'public good' to do so. The QC agreed with the BBFC that the overall purpose of the film was serious and that its explicit scenes were not primarily intended to titillate. Given the critical reputation that the film enjoyed, he therefore concluded that it was highly unlikely to be found obscene by a jury. Nonetheless, he also accepted that the scene in which the young boy's penis is tugged was potentially indecent, even though nothing sexual occurred.

This posed a difficulty for the BBFC because the scene in question was pivotal to the audience's understanding of the female protagonist's shift from mere obsession to derangement. James Ferman therefore sought to alter the scene in such a way as to preserve its meaning, whilst removing any potentially 'indecent' image of a child. The best way to do this seemed to be by 'optically reframing' the end of the scene so that what was happening would be clear, whilst leaving any indecent image just off screen. The BBFC's legal advisers agreed that, legally, the only matter with which the BBFC needed concern itself was 'visual' indecency, rather than 'narrative' indecency (ie what was seen on screen, rather than what was being implied).

The first attempt at reframing was considered unacceptably crude and damaging to the film. Therefore the scene was reworked in a specialist lab, using a more gradual zoom into the characters' faces. With this reframing completed, the film was classified 18 uncut for cinema release in 1991. At the time, the BBFC was also asked whether it would consider granting an 18 certificate for video release. However, given the greater likelihood of the film falling into the hands of children, or being viewed in parts rather than as a whole, the BBFC was unconvinced that the film's immunity to prosecution would be as strong on video. At the time, explicit sex was not permitted even at the R18 category and In The Realm of the Senses was therefore regarded as better suited to cinema screenings where the circumstances of viewing were more able to be controlled.

In 2000, the BBFC was again asked to look at the film for DVD release. By this time, sexual portrayals at the 18 level had become gradually more explicit and recent public surveys had shown that the public felt the BBFC could afford to be more relaxed about sex for adults. Therefore, following on from recent decisions on films like The Idiots and Romance, In The Realm of the Senses was passed at 18 uncut for video and DVD release.  The version submitted to the BBFC in 2000 had been cut by its distributor, prior to submission, in order to reframe the scene of potential indecency involving a child that had caused difficulties in 1989-1991.  Therefore the BBFC was not required to judge that scene afresh.  In 2009, a cinema re-release of the film was also passed at 18 uncut, but this time with the entire scene in which the child appears deleted prior to submission.

It was not until 2011 that the BBFC was asked to judge the full version of the film again, with the 'penis tugging' scene reinstated. 

On this occasion, the BBFC concluded that the scene was not likely to be found indecent under more recent interpretation of the Protection of Children Act and the film was therefore passed 18 uncut for DVD re-release. 

The brief moment of 'penis tugging' does not occur within a sexual context and is not at all sexual or eroticised in nature.  More recent case law has made it clear that mere nudity does not automatically equate to indecency in terms of the Protection of Children Act and a number of films that were cautiously cut in the past have had their original cuts reinstated (eg Pretty Baby, The Tin Drum, Taxi Driver, Rambling Rose, Christiane F, Caligula). 

It is worth noting that the 1991 cinema release of the film comprised the original 'director's cut', whereas all subsequent releases (the 2000 DVD release, the 2009 cinema re-release, and the 2011 DVD re-release) have been of the slightly shorter 'producer's cut' of the film.  The shorter version of the film deletes or shortens six narrative scenes, none of which contain any contentious material.  The explicit sexual scenes for which the film is perhaps most famous are intact in both versions.

In September 2011, the BBFC classified a submission of 'deleted scenes' from In the Realm of the Senses.  This submission comprised the additional scenes that had featured in the longer 'director's cut' version, classified for cinema release in 1991, but which had been absent from subsequent submissions of the film.  The 'deleted scenes' in question are presented within their original contexts, illustrating the material that occurs immediately before and after them.  Therefore, the 'deleted scenes' submission runs at 12 minutes (approx), in spite of the fact the deleted scenes themselves comprise only six minutes of footage (approx).  The 'deleted scenes' were classified 18 uncut, in line with their classification within the context of the film as a whole in 1991.