David Cameron has failed to get the fundamental EU reform which was the basis of the Remain campaign.

It is four months since the prime minister’s ‘settlement’ constituting a so-called renegotiation of the terms of UK membership of the EU.

As the referendum campaign has progressed, very little is now heard from David Cameron and the ‘Remain’ side regarding the settlement. Nor is it now apparently suggested that the settlement constituted the ‘fundamental renegotiation’ and reform of the UK’s relationship with the EU referred to by the prime minister in his Bloomberg speech in January 2013. What value should therefore be placed on the settlement?

Although the UK government has regarded the settlement as a treaty in itself, there can be no doubt that it is not a binding EU treaty under EU law. Even if the settlement binds the parties under international law, it is expressly recognised that it does not bind EU institutions and is not necessarily enforceable under either EU or domestic law. It is open to the European court or a UK court to find an inconsistency between the settlement and the existing EU treaties and decide the case before them on the basis of the pre-eminence of the existing EU treaties.

In part this is due to the nature of the settlement, which consists of a ‘preamble’ and five ‘declarations’ relating to economic governance, competitiveness, sovereignty, social benefits and free movement. Of these, it is the declarations relating to social benefits and free movement which will require formal treaty change and which are subject to existing EU law on social benefits and free movement.

Conflicting views have been expressed as to whether the European court is bound by the settlement. For example, justice secretary Michael Gove has argued that the court is not bound by the settlement until the relevant treaties are changed.

The attorney general Jeremy Wright has opined that the European court would be required to ‘take [the declaration] into account’ in reaching its decisions. Under UK domestic law, the settlement would need to be embodied in legislation to become binding upon the UK courts. Without treaty amendment or a relevant decision of the European court, the settlement would not automatically be enforceable under UK domestic law under the provisions of the European Communities Act 1972.

The declaration relating to economic governance includes provisions that there should be no discrimination against non-eurozone countries, non-eurozone countries will not impede the implementation of new measures such as further integration relating to the eurozone, and non-eurozone countries will not face financial losses due to eurozone bailouts. The agreement does not go as far as incorporating a UK veto.

The difficulty is that without formal treaty change the provision is merely declaratory. Moreover, since the eurozone countries comprise a qualified majority they would undoubtedly wish to prevent the non-eurozone countries such as the UK having a veto over reform measures designed to improve the functioning of the eurozone.

The declaration on competitiveness confirms the aims of the single market and free movement of people, goods, services and capital and provides that EU institutions and member states must take ‘concrete steps towards better regulation’ so as to lower the regulatory burden on businesses. This declaration is less controversial and largely confirms existing pledges and commitments. However, there is nothing tangible that guarantees that the EU will become more competitive.

The declaration on sovereignty purports to end the UK’s obligation to work towards ‘ever closer union in a formal, legally binding and irreversible way’. It also sets out a proposed ‘red card’ procedure whereby 55% of national parliaments will be able to combine to prevent further discussion in the council of the EU of legislative proposals where they believe power should lie with national legislatures in accordance with the principle of ‘subsidiarity’.

The difficulty is that the declaration as to ‘ever closer union’ is simply that; it does not in any way change anything as to how the EU works or the competencies that it has. The ‘red card’ subsidiarity proposal is of dubious practical value. It is limited only to subsidiarity objections and would be unlikely in practice to produce a different outcome from the normal voting rules.

The declarations relating to movement and social benefits are the most problematic, since they are probably contrary to existing EU law.

The proposal to amend Directive 2004/38/EC in order to exclude non-EU family members from the free movement provisions if they did not have a prior lawful residence in a member state before marrying an EU citizen appears to be designed to reverse previous CJEU case law. Even if the declaration can be effectively embodied in EU law (which will require a treaty change) it is likely to be of very limited practical value in controlling large-scale immigration.

The declaration proposing to limit social benefits for up to seven years is almost certainly contrary to existing EU treaties. A person, such as a would-be migrant to the UK from eastern Europe, affected by the denial of in-work benefits would be entitled to bring an application for judicial review in the UK courts and, following a reference to the CJEU, would almost certainly be successful in demonstrating that the so-called ‘emergency break’ on in-work benefits is unlawful under regulation 492/2011.

In summary, the enforceability of the settlement is at best doubtful and its legality dubious since it would require formal treaty change. Treaty change will be subject to ratification in all EU member states including those in which referendums might be required and cannot be guaranteed.

Moreover, it cannot be regarded as the fundamental reform of the EU which the prime minister has claimed and which was, on recent authority, the basis of the Remain campaign.

Clive Thorne is a partner at Wedlake Bell. He is writing in a personal capacity and is a board member of ‘Lawyers for Britain’