Operation Spanner was the name of an operation carried out by police in Manchester in 1987, as a result of which a group of gay men were convicted of assault occasioning actual bodily harm for their involvement in consensual sadomasochism over a ten-year period.
House of Lords appeal
The resulting House of Lords case (R v Brown, colloquially known as "the Spanner case") ruled that consent was not a valid legal defence for wounding and actual bodily harm in the UK, except as a foreseeable incident of a lawful activity in which the person injured was participating, eg surgery.
Subsequent campaigns and legislation
Legal reform and review of the concern is ongoing and the convictions are controversial due to issues of whether a government or oneself is justified to control one's own body in private situations where the only harm is to consenting adults.
The fallout from the Spanner case led to the setting up of the Countdown on Spanner (now SM Pride) and Spanner Trust organisations. A formal petition to de-criminalise acts that temporarily injure a consenting adult was filed with the UK's parliament, then in the Criminal Justice and Immigration Act 2008, S.66 de-criminalised possession of "pornography" which depicts some acts of injurious sex if it involves oneself (and potentially others, except for those who cannot or do not consent), with the burden of proof being on the accused; Spanner Trust noted their happiness with the consent clause in the Sexual Offences Act 2003.
On the other hand, in the Criminal Justice and Immigration Bill 2007, the Government cited the Spanner case (Brown 1994 1 AC 212) as justification for criminalising images of consensual acts, as part of its proposed criminalisation of possession of "extreme pornography".
Experts and advocates besides Spanner Trust have also called for the law to be stated more clearly so that it is applied practically equally from one judge to the next, and to unevoquivocably legalize the minority sexual preference of finding pain pleasurable (algolagnia) for consenting adults.
As a result of the Spanner case, the Law Commission decided in 2007 to investigate the status of consensual sadomasochistic acts in the law of England and Wales.