When countries agree to work together to achieve a common purpose, they agree to accept group decisions rather than retaining specific aspects of their autonomy. They bind themselves because, by doing so, they bind the others in the group in the same way.
The following sub-sections describe different aspects of such an arrangement, using the European Union as the clearest example:
Collaborative legal frameworks (126.96.36.199);
EU law (188.8.131.52);
National sovereignty and EU Law (184.108.40.206);
The European Convention on Human Rights (220.127.116.11);
Rejection of EU law (18.104.22.168).