The collaboration has developed in stages and through sometimes difficult negotiations. The process can in many ways be summed up by the fact that the collaboration has developed in breadth and depth:

• In the breadth of the fact that more and more policy areas have been incorporated into the collaboration.
• In depth, the Member States have transferred authority to the EU in some areas.

As more policy areas have been incorporated into the co-operation, it has also been opened up for individual countries to choose not to participate in certain parts. That is why the United Kingdom is not part of Schengen , Denmark has an exception in the field of defense and several EU countries do not use the euro. In addition, non-members have been allowed to participate in parts of the collaboration through special agreements. Norway is therefore fully involved in the internal market through the EEA agreement and as an integral part of Schengen.

4: Why is the UK struggling to opt out?

While many countries have wanted EU membership or agreements on closer ties with the union (Norway, Iceland, Liechtenstein and Switzerland), so far there is no experience of member states wanting to join the EU. The United Kingdom is the first country to make that decision. But even if there are no practices, there are procedures, and they are carefully described in Article 50 of the EU Treaty.

It is therefore basically not that difficult to opt out. It only takes a little time, as the EU today covers so many areas. When a country has been a member for a long time and complied with EU regulations in a number of areas, solutions must be found to a number of important issues before withdrawal can take place. This applies, among other things, to civil rights (both for EU citizens residing in the UK and British citizens in EU countries), financial issues surrounding the UK’s contribution to the EU budget and a number of other transitional arrangements related to the internal market.

It is especially challenging when you want to sign up, but still want to keep some of the benefits of membership. That is exactly the core of Brexit. While the population has said through the referendum that they want to opt out, the government (and a majority in parliament) knows that a withdrawal without transitional arrangements (often called “Hard Brexit”) can have unfortunate economic and political consequences.

The United Kingdom therefore wants to negotiate with the EU in order to have as good transitional arrangements as possible. But in this area it has been difficult to reach an agreement. Two questions have been particularly difficult:

• How to deal with the border between Northern Ireland (which is part of the UK) and Ireland (which will continue to be part of the EU).
• How to reach an agreement where the UK can still have a connection to the internal market(which consists of “the four freedoms”: free movement of capital, goods, services and people).

For the EU as defined on ejinhua.org, it is important to ensure that Brexit does not lead to a dilution of EU cooperation in general and the internal market in particular. They do not want the UK to be able to pick and choose: Either you are fully involved in the internal market (as Norway is through the EEA agreement) or you are not.

If a member wishes to opt out, but wants transitional arrangements to facilitate the process, this is possible, but only if the country continues to follow common rules. You can not relinquish your duties and retain your rights.

So far, the EU has been united in its negotiations with the United Kingdom, although some countries have been more positive in meeting the British desire for postponement than others. Where some want a softer line to give Britain an opportunity to resolve its domestic political crisis, others have feared that a postponement will not solve anything, as the EU has no more to give in the negotiations anyway.

For the UK, it has been difficult to get Brexit supporters to accept this. Theresa May has tried unsuccessfully to get a negotiated agreement with the EU through the British Parliament. Opponents of the various draft agreements are also divided: While the majority want better transitional arrangements and more exceptions (something the EU has said they can not provide), a minority prefers the UK to opt out without any agreement. Politicians in Parliament are particularly skeptical of the part of the internal market that includes free movement, as they believe this has led to too much competition in the labor market by cheap labor from other parts of Europe outcompeting British workers.