What is sovereignty?
Sovereignty can be understood as the authority of a state to govern itself and determine its own laws. In the UK, we also have the idea of parliamentary sovereignty, which means that the UK Parliament is the highest source of authority to make laws without restriction. Parliamentary sovereignty is unusual, as in many countries parliaments are constrained by written constitutions and a constitutional court, which can review and annul laws that conflict with the constitution. Parliamentary sovereignty was complicated by EU membership, as it constrained some decisions made by Parliament owing to the primacy of EU law. That said, those constraints were freely-entered-into by Parliament itself. The fact that the UK left the EU because of several Acts of Parliament shows that parliamentary sovereignty remained. Outside the EU, the UK is still constrained by its many remaining international agreements, such as membership of the World Trade Organisation (WTO).