Why is the UK or Ireland in the European Union but not in the Schengen area?

When we talk about Schengen Treaty, we must bear in mind that it does not refer to the same as the European UnionHence, there are countries that belong to the continental Union without this forcing them to be included in the Treaty (United Kingdom and Ireland) and vice versa (Switzerland, Norway, Iceland and Liechtenstein).

Special features of the United Kingdom and Ireland

The UK refused to sign the Schengen Agreement. One of their arguments was that, For an island nation, border controls are a better and less intrusive way to prevent illegal immigration than other measures.such as identity documents, residence permits and Police registration, which are appropriate for countries with «long and permeable land borders». Ireland did not subscribe to the Schengen Agreement because «It would not be in Ireland’s interest to have a situation where the common border area with Great Britain would end and Ireland would have to impose entry and exit controls on people traveling between this country and the United Kingdom, also being at the land border. «

When Schengen was signed by the Union in the Treaty of Amsterdam, Ireland and the United Kingdom obtained an option to opt out of the part of the treaty that was to incorporate the Schengen rules into European law. Under the relevant protocol, Ireland and the United Kingdom can apply to participate in aspects of the Schengen group, but this is subject to the approval of the member states of the Treaty.

Specifications of the Schengen area with the particularity of the United Kingdom and Ireland

Differences between the European Union and the Schengen Area

The European Union is a political and economic union of 28 member states. The EU has developed a single internal market without tariffs and guarantees the free movement of all EU citizens between the 28 countries. Although each member state has its own government, there are shared laws that cover a variety of areas including trade, agriculture, and regional development.

The original members (Belgium, France, Italy, and Luxembourg) joined in the 1950s with the signing of the Treaty of Paris (1951) and the Treaty of Rome (1957). They came to be known as «the European Community». The community expanded over the next several decades to include the other 22 members and came to be called the European Union.

The Schengen Area is an area made up of 26 European states that have officially abolished the passport and other types of control at their mutual borders.. For visitors from the European Union, it effectively means that the Schengen Area acts as a singular country, that is, once you enter one Schengen country, you have entered them all.