The European Court of Human Rights has ruled that the so-called 'McLibel Two' should have been given legal aid by the British government.
Environmental campaigners David Morris and Helen Steel were found guilty of libelling the fast-food giant McDonald's in 1997 after being refused legal aid to finance their defence. The case had started in 1994.
They were ordered to pay damages of £40,000 for handing out leaflets attacking the company's working practices and policies.
The Strasbourg-based court ruled they did not receive a fair trial. Its verdict is the end of a separate courtroom fight in which the pair accused the UK government of breaching their human rights.
The 15-year legal wrangle is the longest civil or criminal action in English legal history.
Speaking on RTÉ Radio, Mr Morris said it was a 'victory against attempts to prevent people's right to criticise the rich and powerful who dominate society'.
He said the success of the European human rights case was a vindication of criticism of the fast food giant in the past.