How the WTO works - fullfact.org/europe/introduction-world-trade-organisation/
The WTO has 164 members. The EU is the only organisation to be a member of the WTO. All EU member states are also individual members but they always vote as the EU bloc.
(The exception is the EU which has a block vote of 28, soon to be 27.) So as members of the EU we are a party to a possibility of having more influence on the WTO than individual countries.
Trading on WTO terms
The WTO does not have a set of minimum tariffs or rules with which each country must comply. Instead, it has two main elements.
First, it requires each country to set out a list of its tariff rates for each product and service. Each tariff set for a product and service is subject to negotiation with each other member of the WTO. Whether another member seeks to negotiate these tariffs depends upon whether they have an interest in that product.
For large trading states like the USA, China or Brazil these lists or schedules can be extremely long. The EU has a single schedule for all its members and it is quite extensive. All of these are available on the WTO website.
Second, the WTO requires states to apply their individual schedules, and non-tariff rules on packaging or licencing etc., in a non-discriminatory way.
Most-Favoured Nation and National Treatment rules
This non-discrimination breaks down into two basic rules. The first, Most-Favoured Nation, means you must give whatever your best treatment is for foreign products coming into your country to all members of the WTO. For example, if a country cut the tariff on imports of copper from 10% to 5% for exporters from one country, it would have to charge 5% to every other country as well.
The second basic rule, National Treatment, means that you must give your best internal conditions to foreign products or services. For example, if you do not require domestic products to have a warning as to sugar content in food you cannot require it of foreign products. These requirements are set out in detail in the WTO’s core treaties: GATT (General Agreement on Tariffs and Trade), GATS (General Agreement on Trade in Services) and TRIPs (Trade Related Intellectual Property Rights).
But there is a big exception. If you are in a customs union or free trade area, for instance you can treat products and services from the customs, union better than you treat other WTO members. The EU is an example of a customs union .