Neil Addison at the Religion Law Blog has an interesting post on the recent case of Singh v Singh. He summarises:
Mr Hardeep Singh (Defendant) had written an article in the Sikh Times questioning the religious validity etc of His Holiness Sant Baba Jeet Singh Ji Maharaj (Claimant), accusing him of being the leader of a Cult a Blasphemer and of engaging in religious practices which were incompatible with Sikhism. In response Jeet Singh sued Hardeep Singh for Libel.You can read the case at this link: Singh v Singh  EWHC 1294 (QB)
Mr Justice Eady, in his judgement, pointed out that on what was intended to be the first day of the trial,
a preliminary issue has to be resolved on the second defendant's application to stay the claim, either wholly or in part, as being non-justiciableHe then said:
That issue was pleaded in the defence on 16th November 2007 and is founded on the well-known principle of English law to the effect that the courts will not attempt to rule upon doctrinal issues or intervene in the regulation or governance of religious groups. That is partly because the courts are secular and stand back from religious issues while according respect to the rights of those who are adherents or worshippers in any such grouping. It is also partly because such disputes as arise between the followers of any given religious faith are often likely to involve doctrines or beliefs which do not readily lend themselves to the sort of resolution which is the normal function of a judicial tribunal. They may involve questions of faith or doctrinal opinion which cannot be finally determined by the methodology regularly brought to bear on conflicts of factual and expert evidence. Thus it can be seen to be partly a matter of a self-denying ordinance, applied as a matter of public policy, and partly a question of simply recognising the natural and inevitable limitations upon the judicial function.Later in the judgement, an number of precedents were cited.
In the case of R v Chief Rabbi of the United Hebrew Congregations of Great Britain and the Commonwealth Ex p. Wachmann  1WLR 1036, the decision of Simon Brown J (as he then was) contained the following passage:
"... the court is hardly in a position to regulate what is essentially a religious function - the determination whether someone is morally and religiously fit to carry out the spiritual and pastoral duties of his office. The court must inevitably be wary of entering so self-evidently sensitive an area, straying across the well-recognised divide between church and state.In the case of R v The Imam of Bury Park Jame Masjid Luton & Ors. ex parte Sulaiman Ali (unreported) on 13th September 1991, Auld J (as he then was) followed the approach of Simon Brown J "and said, crisply",
One cannot, therefore, escape the conclusion that if judicial review lies here, then one way or another this secular court must inevitably be drawn into adjudicating upon matters intimate to a religious community".
"In short, the issues raised involve an examination of religious law and the custom and traditions of a particular local religious community which the court is not competent to undertake".That judgment was ultimately upheld by the Court of Appeal reported at  COD, page 142.
More recently, there was the decision of Gray J. in Blake v Associated Newspapers  EWHC 1960 (QB). At paragraph 21 the learned judge said this,
"It is well established ... that the court will not venture into doctrinal disputes or differences. But there is authority that the courts will not regulate issues as to the procedures adopted by religious bodies or the customs and practices of a particular religious community or questions as to the moral and religious fitness of a person to carry out the spiritual and pastoral duties of his office".In short, m'learned friends at the Queen's Bench would be unlikely to accept the task of adjudicating whether it is or is not defamatory to call Mgr Basil Loftus a heretic, or whether there is a defence of justification, i.e. that the statement is true; or of fair comment, i.e. that it was an expression of opinion, based upon true facts, made in good faith and without malice. (For further information on the law of libel and slander as it relates to the media, see Carter-Ruck Media Law Questions and Answers.)