THE PROSPECT of a government mauling by prominent Conservative peers has obscured the most important issue in the Lords' consideration of the European Communities (Amendment) Bill. This is not whether the Bill should be passed, but whether peers should attach a clause requiring it to be put to a referendum before the Maastricht treaty is ratified.

Article 247 of the Treaty on European Union requires member states of the Community to ratify Maastricht 'in accordance with their respective constitutional requirements'. Douglas Hurd has argued that, while the Danish, French and Irish constitutions require or allow for a referendum, in Britain it is Parliament that decides.

This argument is, constitutionally, highly dubious. There have, so far, been three referendums in Britain: the Northern Ireland border poll in 1973, the referendum on the European Community in 1975 and the devolution referendums in Scotland and Wales in 1979. Each of these was concerned with the transfer of parliamentary powers, either by excluding a part of the United Kingdom (Northern Ireland) from Parliament's jurisdiction, by limiting Parliament's right to legislate (Scottish devolution), or by transferring powers to another body (the European Community).

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There is a clear constitutional rationale for requiring a referendum in such circumstances. MPs are entrusted by the electorate with legislative power, but they are given no authority to transfer that power. That authority requires a specific mandate from the people. 'The Legislative,' declares John Locke, in that bible of liberal constitutionalism, the Second Treatise of Government, 'cannot transfer the power of making laws to any other hands. For it being but a delegated power from the People, they who have it cannot pass it to others.'

The House of Lords, however, is bound by the so-called 'Salisbury Convention', formulated during the 1945-51 Labour administration by the Marquess of Salisbury, leader of the opposition in the Lords. This convention declares that peers should not frustrate a measure that has been foreshadowed in the government's election manifesto, since such a measure could be deemed to have received popular approval.

The ratification of the Maastricht treaty was, of course, advocated by the Conservatives in their 1992 manifesto; but so it was also in the manifestos of the other main parties. There was, in effect, no way in which a voter opposed to ratification could express that opposition. Ministers, therefore, are in no position to claim a mandate for ratification of Maastricht, and peers are under no obligation to exercise self- restraint. The Salisbury Convention simply does not apply.

A second argument made by Douglas Hurd is that it would be undemocratic for a non-elected chamber to require a referendum, as decisions on matters connected with elections ought to be reserved for the Commons. A second chamber, however, exists to allow governments to reassess issues, particularly constitutional issues. In 1978, the Conservative Review Committee on the House of Lords, set up by Margaret Thatcher and chaired by Lord Home, insisted that the House of Lords was 'a constitutional safeguard'; for on constitutional questions in particular its purpose was 'to make sure that there really was a majority in the country for major changes in the way in which it is governed'.

This is a democratic justification for the use by the second chamber of its powers. By requiring a referendum on Maastricht, peers, far from thwarting the will of the people, would be allowing that will to be constitutionally expressed.

But there is a deeper reason why the Lords should attach a referendum clause to the European Communities Bill. Most of those who favour a referendum wish to see Maastricht defeated. Paddy Ashdown is almost the only leading supporter of Maastricht to have come out in favour of a referendum, although the Liberal Democrats, like the other parties, are divided on the issue.

It is, however, a profound error for supporters of closer European co-operation to oppose an appeal to the people. So far, the development of the Community has been characterised by a process of elite decision-making insulated from popular pressures. The leaders led and the people followed. The Danish and French referendums, however, together with poll findings showing increasing scepticism towards Maastricht, raise the question of how the Community is to progress when the leaders lead but the people no longer wish to follow. 'Europe,' Jacques Delors has argued, 'began as an elitist project . . . (in which it was believed) that all that was required was to convince the decision-makers. That phase of benign despotism is now over.'

The European Community will not retain legitimacy unless it can mobilise popular consent. If its leaders try to build Europe against the wishes of their people, they will fail. If Mr Major tries to propel Britain towards European union without popular support, he will deserve to fail. That, in the last resort, is the case for Maastricht to be ratified by referendum.

Thus the House of Lords has not only the right but also the duty to require Maastricht to be put to the voters. In allowing the electorate to decide, the Lords would be striking a blow not only for democracy in Britain, but also for a new Europe, a people's Europe, in place of a technocratic Community that has became increasingly remote from those whom it purports to serve.

The writer is reader in government at Oxford University and a fellow of Brasenose College, Oxford.