Former inmate asks lawyers to start proceedings for compensation after prime minister said he would not change law
John Hirst, the former prisoner who took the original case, said he had asked his lawyers to start proceedings for compensation in the wake of Cameron's comments last week.
The British government has until 22 November to respond formally to the ECHR ruling, and despite Cameron's strong public line there is a dispute inside the government on how to act.
Hirst's lawyers are writing to the Strasbourg court to bring to its attention the prime minister's comments. Cameron told MPs he might allow parliament another chance to vote on the issue to show the ECHR it had considered and rejected its opinion.
Hirst told the Guardian: "All three arms of the state, executive, parliament and judiciary, were found guilty of a human rights violation.
"The UK is required under international and European law to remedy the breach and prevent it happening again. In addition, English public law states that one of the roles of the state is to secure human rights.
"The Council of Europe states, and the UK agreed in the Brighton declaration, that the primary responsibility for human rights falls upon member states.
"What this case discloses is that there is a systemic failure in the UK, a structural fault, which needs to be fixed.
"When the Council of Europe identifies this situation in a member state it identifies the problem and advises what action needs to be taken to remedy the breach. In this case it is to amend section 3 of the Representation of the People Act 1983 to allow convicted prisoners to vote. My case shows that section 3 is not compatible with article 3 of the ECHR's first protocol.
"So either the UK complies or withdraws from the Council of Europe and the ECHR."
The justice secretary, Chris Grayling, speaking about the row for the first time, took a cautious approach, saying: "I have to be very careful in my role as justice secretary and lord chancellor. The reality is that we are signed up to the European convention on human rights. We are signed up to the European court of human rights. If, therefore, we choose to disagree with a ruling from that court, we have to understand that we are taking a significant step outside that international commitment."
Speaking on the BBC's Andrew Marr Show, he added: "There are precedents from other European countries of them saying 'no, we don't agree with you' to the European court of human rights, but of course the counter-argument is that if we send a message that says we will stand up to the court, where does that leave countries in other parts of Europe that perhaps have less good human rights records than we do, where there are really quite serious issues about the right to a trial?"
Grieve, the attorney general, said in a lengthy speech last week that he disagreed with the ECHR judgment in the prisoner case, and acknowledged that the British parliament was sovereign in the matter.
But he cautioned: "Observing its judgments is an international legal obligation arising by treaty … it is possible for parliament to take no action on the judgment, although that would leave the government in breach of the treaty and liable to criticism and sanctions from the Council of Europe by its fellow signatories and to damages awarded by the court.
"Some have also argued that the solution for the UK in view of these problems is to withdraw from the convention altogether on the grounds that it is an undesirable and unnecessary fetter of national sovereignty in decision-making. I disagree. Withdrawal would result in reputational damage."