Europe’s highest court has parked an issue that might have confounded any move by a future government to withdraw from the European Convention on Human Rights (ECHR), by declaring that the EU’s plan to join the convention in its own right is unlawful.

In an opinion published today, the Court of Justice of the European Union says that a draft agreement for accession under the Treaty of Lisbon lacks provisions to ensure EU law is not compromised – and might risk ‘adversely affecting the division of powers between the EU and its member states’.

The opinion points out that, while the Treaty of Lisbon removed the problem of the EU’s accession to the convention lacking legal basis as the EU is not a state, the draft agreement creates new conflicts. For example by treating the EU as another convention state it ‘specifically disregards the intrinsic nature of the EU’.

For example, the ECHR would require each EU member to check that the other member states were observing fundamental rights, even though EU law imposes an obligation of ‘mutual trust’ between member states. ‘In those circumstances, accession is liable to upset the underlying balance of the EU and undermine the autonomy of EU law.’

Among half a dozen other objections, the court says the agreement has no provision to ensure that any move to lay down higher standards of protection than those guaranteed by the convention is coordinated with the EU Charter of Fundamental Rights, as required by the charter. 

The decision is likely to be welcomed by the Conservative party, which is currently drafting a ‘British bill of rights’. Legal commentators have pointed out that, if a future Conservative government were to leave the ECHR, EU accession would still leave UK residents a route to the European Court of Human Rights in Strasbourg.