The crucial point is that you need a trade deal to make use of Article 24 and that the EU would not have to agree anything with the UK after a Brexit without a deal. The answer is that it is possible. The UK and the EU can conclude a temporary free trade agreement that is only expected to last until the full free trade agreement is negotiated and concluded. A temporary free trade agreement that deals only with tariffs can be extremely simple. Dr. Lorand Bartels, an expert in commercial law at the University of Cambridge, presented a unilateral draft of this type of agreement. If the EU has a „mixed jurisdictions“ trade agreement with a third country and is blocked by non-ratification by one or more Member States, the EU can conclude an interim trade agreement with that country and, in practice, from time to time. Such an interim agreement will contain only the parts of the comprehensive free trade agreement that fall within the scope of the EU`s contractualisation prerogatives. This use of the term „interim“ has nothing to do with the interim agreements under Article XXIV of the GATT, but simply means that the agreement will remain in force until it is replaced by the ratification of the free trade agreement in full mixed jurisdiction.
The EU`s chief negotiator, Michel Barnier, said it would not be possible to start future trade negotiations until an agreement is reached on three key issues: citizens` rights, the Irish border and the UK`s financial commitments. Article 24 is a provision of the General Agreement on Tariffs and Trade (GATT). THE GATT is a World Trade Organization (WTO) agreement to reduce tariffs and other trade barriers around the world. Normally, under WTO rules, tariffs and other barriers to products from other countries must be the same for all WTO members. This is considered the principle of the most favoured nation. However, the GATT offers members several ways to negotiate agreements with each other, to selectively remove barriers without having to apply the same benefits to all WTO members: one of them is Article 24. Its main objective is to ensure that these agreements do not mean obstacles to other WTO members. In principle, Article 24 also allows members to enter into „intermediate agreements“ to enable them to offer preferential treatment before a full agreement is implemented. Article XXIV authorizes a derogation from this principle of the MFN, which applies where countries or regions agree to a free trade agreement (FTA) covering „essentially all trade“ between them. The EU is an example of a free trade agreement. Article 24 of the GATT forms the basis of two or more territories for the construction of a customs union or the construction of a free trade agreement.
It also provides for an interim agreement necessary to establish a customs union or free trade area. It depends on the terms of the free trade agreement and what is agreed between the parties. Because of this level of oversight by dozens of WTO members and the WTO organization, GATT Article XXIV has never been used for interim trade agreements since the creation of the WTO in 1995. Instead, countries prefer to introduce „comprehensive“ free trade agreements with an implementation period in order to circumvent the high level of control that would be applied to them. However, any free trade regime must not degrade the terms of trade for non-participants and result in higher tariffs or trade restrictions than before. Therefore, any customs union or free trade agreement must be notified to the WTO in order to allow other WTO members to raise their concerns. Like defence unions and free trade agreements, the WTO must be informed of an interim agreement, but the rules are stricter: members can request changes if they are not convinced that the interim agreement will actually lead to a full agreement within the proposed time frame.