From 2010, all UK passport applicants will be issued with biometric ID cards. Baroness Williams, the Liberal Democrat peer, recently said that as the cards would seriously undermine individual liberty, people were entitled to peacefully refuse to co-operate. She said she would rather go to prison than carry an ID card.

Conscientious objection is a difficult challenge for the law. According to one view, the law shouldn’t tolerate any disobedience. If we give exceptions to people whose consciences demand they disobey the law, where would it lead? People might adopt all sorts of stances and say things like “my conscience demands I vandalise gas guzzling cars”, or “I don’t recognise that the law of murder should apply if my daughter brings shame on my family”.

The law has, however, permitted conscientious objection in some circumstances. For example, allowing people not to fight in wars, and to be excused religious assemblies in schools when they were compulsory.

The Statute of Winchester 1285 obliged every free man between the ages of 15 and 60 to fight for the Crown if required. Quakers had been given some concessions not to engage in combat under the 1802 Militia Act, but the right not to fight in war for reasons of conscientious objection (subject to proof) was first conferred in Britain under section 2(1) of the Military Service Act 1916. About 10,000 objectors were excused service and another 6,000 sentenced to prison with hard labour.

In a curious twist of British eccentricity, when the objectors were eventually released, they got a letter from the War Office saying that their behaviour had been so bad that if they ever applied to join the Army again they’d be imprisoned.

The conscription during the Second World War, under the National Service (Armed Forces) Act 1939, was more wide-reaching. From 1941, conscription also included women. Under the rules 48,000 people became conscientious objectors. The public was more understanding about conscientious objection than it had been in the First World War, and the government tried to fit objectors into useful work which they could perform. The cases to avoid combat duties (from people in the Peace Pledge Union, religious groups and radical working class groups) were heard by tribunals chaired by judges.

The tribunals could fall into difficulties if they relied too much on mechanically going through standard questions. Sir John Mortimer, QC, has noted that one of the favourite panel questions to someone trying to avoid fighting on grounds of conscience was, “What would you do if you saw a German raping your grandmother?” The proposed reply of one of Sir John’s friends was, “Wait until he’d finished and then bury the dear old lady again”.

In 2006, the Court of Appeal ruled, in effect, that it was unlawful for people (the Peace Tax Seven) who conscientiously objected to the war in Iraq to withhold from the Inland Revenue the proportion of their tax that they said would have been spent on arms. The seven, including Siân Cwper, from Gwynedd, Wales, argued that it was against human rights law to make them pay tax into a fund from which expenditure could be made on war.

In their argument, they invoked Article 9 of the European Convention on Human Rights. It says everyone has the right to freedom of thought, conscience and religion, and that this right includes freedom to “manifest his religion or belief” in practice. They didn’t seek any exemptions from paying tax, they just wanted to pay it in full into a pot for peaceful purposes only. Rejecting their case, the court said that under current European human rights law, governments are not bound to create such separate funds.

Today, many parts of law have become so carefully adapted to conscience that there isn’t a need for anyone to disobey. So, for example, under the Oaths Act 1978, any witness who doesn’t want to swear a religious oath ("I swear by almighty God . . . ") to tell the truth can instead make “a solemn affirmation”.

While the law is made to apply to everyone, there might be good reasons in a civilised society for allowing exceptions on the basis of deeply held principle. But there must be appropriate proof of such principles. Citizens must, in general, all serve on a jury if required but one of the exceptions, recognised in guidance issued under the Juries Act 1974 is that excusal can be granted to people whose “ideology or beliefs are incompatible with jury service”.

But evidence for such beliefs must be provided. The law requires evidence of belief to stop someone from benefiting from what Groucho Marx encapsulated in his Duck Soup line: “Those are my principles. If you don’t like them, I have others.”

Professor Gary Slapper is Director of the Centre for Law at The Open University

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