Last night, the English Supreme Court ruled that the Scottish government cannot hold an independence referendum. Having said that Scotland is not a colony, they then turned around and effectively said that they are, by forbidding them from holding a democratic vote on their own constitutional arrangements unless another country says they can.
Pretty obviously, this is incompatible with any notion that the UK is a democratic country, let alone a voluntary union. In a voluntary union, the parties can choose to leave. Instead, Scotland is locked in, trapped in a cage unless England decides to let it out. They're handcuffed to a partner who economically abuses them. Which makes the need and desire to break those chains even stronger.
But the ruling goes further than that. Because the Supreme Court's logic of looking at the extended (rather than strictly legal) effects of a Scottish law for constitutional impacts can apply to other things. For example, Scotland has a democratic system of government, rather than Westminster's backward first-past-the-post. It has lowered the voting age to 16. While the legal effect is restricted to Scotland, each of these presents an alternative, and implicitly makes a moral case for it, putting pressure on Westminster to change its rotten constitutional system. That is, they affect the Parliament of the United Kingdom. Will Scotland's domestic policies now be micromanaged by England to stop Scotland from making them look bad, on the basis that everything is constitutional?
Scottish First Minister Nicola Sturgeon has said that the SNP will run a de-facto referendum on independence at the next available election, and polling is already saying that they will receive more than 50% support. So there's going to be a democratic mandate for independence whether Westminster wants one or not. The next question is whether they will recognise it, and allow Scotland to leave peacefully and democratically, or whether they ignore the expressed democratic will of the Scottish people, and effectively announce their intention to retain Scotland by oppression and force?