Christian Voice wants to bring a case against Mark Thompson, the director general of the BBC, and Jonathan Thoday, producer of the award-winning musical, for blasphemous libel, but was refused permission by City of Westminster magistrates court. The group is hoping to launch what would be only the third prosecution in more than 80 years for an offence which carries a maximum sentence of life imprisonment.

The last successful prosecution was brought by Mary Whitehouse in 1977 against Gay News for publishing a poem, The Love that Dares to Speak its Name, about a Roman soldier's homosexual love for Christ. The human rights group Liberty, which has been allowed to intervene in the high court judicial review, says the law is outdated and argues that free speech rights must protect sacred, profane and secular language alike.

Blasphemy, originally part of canon law, became a common law offence in the 17th century. Paul Stevens of Olswang, the law firm representing Thoday, said the producer's legal team would argue that allowing a prosecution for blasphemy would contravene article 10 of the European convention on human rights, which guarantees the right to free speech.

Stephen Green, national director of Christian Voice, said in 2005 that the show portrayed Jesus as a "coprophiliac sexual deviant". A coprophiliac is someone who is sexually aroused by faeces. The British musical, based on the US television programme, was performed at the Edinburgh Festival in 2002. It moved to the National Theatre in 2003, and then to the West End. It toured the UK for 22 weeks in 2006, and is now showing in New York. The BBC televised the opera in 2005.