Judgment likely to spark clash with UK government, which has ignored similar rulings from the non-EU European court of human rights

Britain’s blanket ban on prisoners being allowed to vote is expected to be ruled unlawful on Tuesday morning by the EU’s highest court, challenging David Cameron’s long defiance of similar human rights rulings.

The judgment expected in the European court of justice in Luxembourg has been brought by a French convicted murderer, Thierry Delvigne, who claims a ban on him voting in elections, including European elections, violates the European charter of fundamental rights.

The prime minister has already said Britain will ignore the implications of the ruling by the ECJ as he has similar rulings by the European court of human rights in Strasbourg, which is not part of the EU but the Council of Europe.

While Britain has been able to ignore the repeated Strasbourg rulings that it is unlawful to deprive prisoners of the vote, the ruling by an EU court is likely to spark a more direct clash with the British government as it is regarded as legally binding on EU member states.

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Cameron has said that the idea of prisoners been given the right to vote makes him “physically sick” and the matter should be left to national parliaments to decide.

But a preliminary opinion by the European court of justice’s advocate-general this year said that national governments have a right to set their election rules provided they do not “prescribe general, indefinite and automatic deprivation of the right to vote” and inmates have access to an appeal against the ban.

In August, the British government officially informed the European court of human rights that it was waiting for Tuesday’s ruling in the French case before taking any further action on the original 2005 British case in Strasbourg. In a series of rulings since then, the human rights court has repeatedly said that prisoners serving shorter sentences should be given the right to vote.

Britain is the only western European country with a blanket ban on prisoner voting, with only Armenia, Bulgaria, Estonia, Georgia, Hungary and Russia in the Council of Europe imposing similar restrictions. Prison reform groups have argued that Britain’s ban has its origins in Victorian ideas of “civil death” being imposed on convicted prisoners.