Bill Cash MP - whose sole activity in the House of Commons seems to be to campaign against everything to do with Europe - has had some success on the Conservative benches with his plan for a Bill that would oblige British courts to give primacy to British statutes over European law whenever there may be conflict between the two.

No doubt this is appealing to those who do not give much thought to the issues involved. But its effect would be to undermine the primacy of European law, which is one of the foundations of the European legal system.

The reason for the primacy of European law is that there is actually not much point in us agreeing with other countries on common rules if each country is then free to ignore them. What would be the point?

The whole purpose of having common rules for the common market or common environmental standards is that we all live up to what we agree in the European context. Divergent national rules would soon end the single market which successive British governments have proclaimed to be vital to our prosperity. Allowing countries to ignore agreed environmental standards and free-ride on the efforts of others is also not something to commend.

Nor should we forget that we rely on the primacy of European law in other countries. Britain won its our court case against France over its ban on British beef thanks to the primacy of European law. If French law had primacy, then they could have continued to ban our beef in complete violation of the rules we had agreed for the common market.