Today, by a majority of 8 to 3, the Supreme Court rules that the government cannot trigger Article 50 without an Act of Parliament authorizing it to do so. Put briefly, the reasons given in a judgment written by all 8 justicers majority are as follows: Section 2 of the 1972 Act provides that whenever EU institutions make new laws, their new laws become part of UK law. The 1972 Act therefore makes EU law an independent source of UK law until Parliament decides otherwise. Therefore, when the UK withdraws from EU treaties, a source of UK law will be cut off. Further, certain rights enjoyed by UK citizens will be changed. Therefore, the government cannot trigger Article 50 without Parliament authorizing that course. We reject the government's argument that Section 2 caters for the possibility of the government withdrawing from the EU treaties.

There is a vital difference between changes in UK law resulting from changes in EU law. And those are authorized by Section 2. And changes in UK law resulting from withdraw from the EU treaties. Withdraw affects a fundamental change by cutting of the source of EU law as well as changing legal rights. The UK's constitutional arrangements require such changes to be clearly authorized by Parliament. And the 1972 Act does not do that. Indeed it has the opposite of fact. The referendum is of great political significance, but the Act of Parliament which established it did not say watch it happen as a result. So any changing in the law to give the effect of referendum must be made in the only way permitted by the UK constitution, namely, by an Act of Parliament. To proceed otherwise would be a breach of settled constitutional principles stretching back many centuries.