This article was orginally published in The Guardian on 15th January 2013.

The European court of human rights ruling on four cases brought by Christians may force changes in legislation and work practices.

The extent of religious freedom within the UK – including the right to wear a Christian cross at work – will be defined by a landmark judgment from Strasbourg on Tuesday.

The long-anticipated decision by the European court of human rights (ECHR) will resolve four controversial cases brought by Christians who claim they were discriminated against because of their faith and prevented from exercising their right to freedom of religion. If any of the appeals succeed, they may force a change in UK legislation and work practices.

The challenges have been brought by: Nadia Eweida, a British Airways worker from London; Lilian Ladele, a local authority registrar also from London; Shirley Chaplin, a nurse from Exeter; and Gary McFarlane, a marriage counsellor from Bristol. The latter two are being directly supported by the Christian Legal Centre (CLC).

Eweida and Chaplin’s cases relate to the visible wearing of crosses at work. The other two are concerned with protection of Christian conscience in the professional arena.

McFarlane was dismissed from his job after indicating he might have a conscientious objection to providing sex therapy to a same-sex couple on account of his Christian faith. Ladele was disciplined by Islington council for not being prepared to conduct civil partnership ceremonies.

The disputes, which have become highly politically charged, resulted in David Cameron telling the Commons last summer that he would change the law on wearing religious symbols if necessary.

“I fully support the right of individuals to wear religious symbols at work,” the prime minister told MPs, adding: “It is a vital religious freedom.”

Andrea Minichiello Williams, CLC director, said:

“These are landmark cases and we have waited a long time to get to this point. At stake is not only the future shape of Christian involvement in community life but the protection of important personal freedoms in a diverse society.”

Lawyers stressed the need for the courts to balance competing rights. Ronnie Fox of City employment law firm Fox told the Guardian: “Employers and their legal advisers are hoping for clear guidance from Strasbourg as to what amounts to reasonable accommodation of religious beliefs.

“There are two key conflicts which need to be resolved. One is the conflict between the freedom of employees to hold and manifest their religious beliefs … in the workplace, and complying with the duties which go with the job.

“The other is the potential conflict between the European convention on human rights and the way in which the convention has become part of domestic English law as a result of the Equality Act 2010 and cases in the English tribunals.”

Ray Silverstein, a partner at the law firm Browne Jacobson who specialises in employment law, said:

“Two of the cases demonstrate the balance to be struck between allowing an employer to set a uniform policy and the ability of an employee to manifest their religious or philosophical beliefs.

“The court could conclude that every uniform policy includes a reasonable adjustment type term to encourage employers to accommodate the wearing of a religious symbol unless there are fair grounds to refuse. Imposing absolute rules is unlikely to be attractive to the ECHR.

“The court should have less difficulty with the two refusal cases. Both employees accepted jobs with duties that required them to serve the public without discrimination. As the employee’s beliefs inhibited them from doing so for the very reason made illegal by discrimination law, it seems likely that the court will uphold their dismissals. However, if any of claims are upheld UK law might have to be changed.”

This article was amended on Tuesday 15 January 2013. The original headline incorrectly referred to the EU when it should have referred to the European court of human rights.