The full challenge to the convictions, which were upheld by the House of Lords in March 1993, is expected to be heard later this year, after yesterday's preliminary ruling by the Human Rights Commission.
Three members of the ring, Colin Laskey, 52, a former teacher, Roland Jaggard, 47, a former aerospace engineer, and Tony Brown, 58, a retired local government officer, have appealed to Europe on the grounds that the prosecution was a breach of their right to privacy.
John Wadham, legal officer of the human rights pressure group Liberty, described the British courts' rulings against the men as "very wide and worrying", while the Government's adviser on legislation, the Law Commission, has already recommended changing the law in the light of the case. It has been argued by lawyers that whipping, scratching or even biting during sex may be illegal.
All the convictions stemmed from a police raid in 1987 on an unconnected matter. They stumbled across videotapes showing group sex, sex with animals, and men's genitals and buttocks being cut with scalpels, branded with hot wires, nailed to boards, punctured with pins, stung with nettles and hit with rulers and spiked gloves. The officers were initially convinced they had stumbled on `snuff movies' and a ritual abuse ring, but after interviewing scores of men they discovered, to their amazement, that every participant was willing, and none had needed hospital treatment.
When the case brought by the Scotland Yard Obscene Publications Squad reached the Old Bailey, Judge James Rant sentenced eight of the 15 sado-masochists to jail in December 1990 for offences under the 1861 Offences Against the Person Act. He said: "Much has been said about individual liberty, but the courts must draw the line between what is acceptable in a civilised society and what is not."
Lord Lane rejected the men's appeal in February 1992, disposing of the defence of consent by quoting an earlier Appeal Court judgement which had outlawed fights between adults who agreed to "step outside" to settle their differences because there was "nogood reason" for their assaults to be allowed. Lord Lane said: "The satisfying of sado-masochistic libido does not come within the category of good reason." The fact that the injuries on ring members were not serious did not matter. They co uld only be excused if they had been "transient or trifling".
The Law Commission recommended earlier this year that the law should be changed to allow sado-masochists to inflict certain forms of injury on each other for sexual pleasure.
Since the case, consent to such practices has been no defence to charges of wounding or assault causing actual bodily harm. The Law Commission said the legislation as defined by the ruling was too strict; consent is now only a defence in a few special circumstances such as boxing, where blows are exchanged "for good reason".
The commission suggested two possible reforms. First, altering the law to allow people to consent to injuries which caused injury, but not serious injury. It would be for a court to decide what was "serious".
Alternatively, the commission proposed extending the range of activities where consent made actual bodily harm lawful. Currently, these include the rather vague "horseplay", tattooing, ear-piercing and sport.Reuse content