As Treaty changes are not on offer, the Government wants to secure “a legally binding and irreversible agreement” , which is believed to be possible due to the Danish and Ireland precedents. The EU has indeed accommodated the Danish and Irish requirements over Maastricht and Lisbon respectively by adopting decisions addressing their concerns, which were subsequently included into Protocols attached to the Treaties. These were decisions adopted by the Member States’ Heads of State and Government, meeting within the European Council, binding as an international agreement.

The so called “legally binding and irreversible agreement” would be therefore an international agreement. The registration in the Treaty Section of the UN Secretariat is indeed a prerequisite for an international agreement to be legally binding. However, under the dualistic theory of incorporation of international treaties, international agreements need to be ratified so that a state can assume the international obligations enshrined in it.

The depositing of the Decision at the UN is a red herring as this would be an international agreement which concerns the autonomous EU legal order and falls primarily under EU law, as interpreted by Member State courts and the ECJ. Such decision would not be part of EU law and it would not be legally binding on the European Court of Justice and the other EU institutions. It would have to be incorporated into a protocol to be attached to the EU Treaties and ratified by all member states in order to become part of the Community legal order.

Thus, until this happens there is no insurance that the renegotiation package that has been agreed will be complied with by the EU institutions and other member states, as it could be easily retreat from member states successor governments with different views, in fact it might be challenged by the other member states or struck down by the ECJ after the referendum takes place.

Such decision, as an act adopted by representatives of the Member States acting not in their capacity as members of the Council but as representatives of their governments is not enforceable because the European Court of Justice has no competence to rule on the compliance of the agreement.

In order to ensure its enforceability Steve Peers has suggested that Article 273 of the TFEU should be used to provide the ECJ with jurisdiction to give binding rulings as regards all or some of its provisions. However, the Court would protect the unity of EU law and would require the application of such agreement to be consistent with EU law. Hence, a ruling against the UK would be most likely.

The European Court of Justice has no competence to rule on the compliance of the agreement but, the EU leader’s decision on the UK’s renegotiation would be subject to its binding interpretation, which has competence to consider any potential conflict with the EU treaties. The ECJ might come across the decision on the UK renegotiation while ask to interpret the treaty provisions through the preliminary ruling procedure. It is important to stress that the European Court is the sole interpreter of EU law and it is not bound by the decision. The ECJ might refer to it as an aid to interpretation of the Treaties but it is not obliged to interpret the Treaties in line with it. In Rottmann the Court of Justice indicated that the European Council’s interpretative declarations and decisions should be ‘taken into account’ in interpreting the Treaty, but then went on to decide in a way clearly contrary to the Danish decision, ruling that ‘Member States must exercise their powers in the sphere of nationality having due regard to European Union law’.

The so called “interpretative decision” would not be EU law and would have no binding legal effect until it is incorporated into a protocol and ratified by all Member States.

On the other hand, it must be stressed that these decisions of the Heads of State and government cannot modify the Treaties, only formal treaty amendments can do so. The ECJ has ruled that the Treaties can only be amended by means of the procedures contained in Article 48. Hence, any decision that intends to achieve the same objective by a different process, and which renders certain aspects of the Treaty process ineffective, would be seen as incompatible with that process. One could say that a decision on the UK renegotiation, would not be compatible with the EU Treaties if its purpose is not to clarify, as in the Irish Guarantees, but to amend the treaties.

The ECJ would be likely to find that such decision affects the internal legal order of the EU. As the ECJ has confirmed the principle of primacy of EU law over international agreements, any agreements concluded between the Member States are to be set aside by national courts when conflicting with EU law.

The Danish and Irish Decisions are not really precedents for the UK, as they did not contradict the EU treaties or required their revision. As Jean-Claude Piris argued, promises of future treaty change will not work if they contradict the existing treaties. It is important to note that Denmark as well as Ireland were trying to ratify the treaties, Maastricht and Lisbon respectively. They were seeking guarantees which they thought had to be met before their people could be asked to vote again in a referendum. Denmark and Ireland had more leverage as the other member states wanted the treaties to enter into force. Nonetheless, whilst the other member states were prepared to accept certain measures so that the Maastricht and Lisbon Treaties could be passed in second referenda, they were unwilling to make any changes to the Treaty already agreed, which would require the re-opening of the intergovernmental negotiations.

In the Danish and Irish cases the EU leaders adopted a decision on the meaning of the Treaty, deciding that the Treaty had no effect on certain aspects of those countries national law. It was emphasised that they were interpretative decisions, whose main purpose was to clarify but not to amend the Treaties. In fact, the Danish and the Irish Decisions have not changed the substantive nature of the treaty itself and it did not change in substance those countries obligations under the treaties, but clarified their implications and limitations regarding particular issues relevant to the Danish and Irish people.

Hence, one can only wonder whether the Danish and Ireland Decisions are real precedents for the UK, as some of the UK Government’s reform proposals would have a substantive impact on the EU treaties, not only as they apply to the UK, but they also would have an impact on other member states national interests, such as demands on free movement. In fact, most of the Government’s reform demands do require treaty changes in order to secure a change in the UK’s relationship with the EU.

Hence, the so called “interpretative decision” can only work if the Government is not serious about changing the treaties and would be happy with a protocol just clarifying treaty provisions as regard the UK. A similar decision to Ireland could be taken with regard to the UK on ever closer union clarifying that this phrase does not apply equally to all member states. In fact, the most David Cameron can expect from the other member states is a decision enshrining the European Council’s June 2014 conclusions about different paths for different countries, which must be then incorporated into a Protocol attached to the EU Treaties at a future date.

Andrew Duff pointing out that under Article 48(2) “only the Commission, the Parliament or a member state government (and not the European Council) … can submit to the Council proposals for the amendment of the treaties” and noting that “the President of the Commission, being a member of the European Council, can indeed be bound by a decision of the European Council”, he believes “Any Brexit agreement, therefore, should command the President of the Commission to trigger the Article 48(2) process if (and only if) the British in their referendum have said Yes to staying in the Union.” He then stressed “Such a pragmatic formula would likely to be accepted by the Court of Justice as a reasonable fix in the circumstances, being as near as possible to legally-binding without actually having changed the treaties. Jean-Claude Juncker should be happy to oblige. And the European Parliament should welcome the breaking of a deadlock on treaty change.” I believe this is not a solution. Even if Junker accepts instructions from the European Council to put forward amendments to the Treaties according to David Cameron demands there is no guarantee this would be appeased by the CJEU and it would not oblige Member States to be in favour of the treaty changes.

According to Steve Peers a Decision of the Heads of State and Government could also address changes to EU secondary law. However, the Commission is in charge of putting forward proposals to amend existing legislation. Hence, even if the European Commission puts forward a proposal amending secondary legislation there is no guarantee such proposals would address the UK’s concerns. Moreover, any proposal to amend EU legislation will be subject to the Ordinary legislative procedure and QMV.

Furthermore, the ordinary legislative procedure enables the European Parliament to override a decision taken by the Council. For instance, the European Parliament will consider any proposal intended to limit access to social benefits as a restriction to freedom of movement. The MEPs won’t agree to restrict free movement and limit access to benefits. Hence, the UK would not be able to get the European Commission, the other Member States, and the European Parliament to agree to a satisfactory change to the EU secondary law.