As a matter of UK law, Parliament is sovereign. No other body has higher standing. Parliament can make any law it likes. The only thing it can’t do is bind its successors.

When the UK joined the European Community (as it then was), Parliament agreed to accept the supremacy of European law. It did this by making the European Communities Act 1972 (ECA). Parliament considered whether to include a section in the ECA that would stop future Parliaments making laws that breached, or purported to have primacy over, European law, but it decided not to do this. Parliament can’t bind its successors. If a future Parliament wanted to breach European law, it could by (i) relying on the implied repeals rule (if Parliament makes two conflicting laws, the second impliedly repeals the first); or (ii) amending or revoking the ECA. So: even if a prohibition of this kind was desirable, it wouldn’t work.

When Parliament made the ECA, it chose to temporarily limit its sovereignty by (i) making a UK statute that allowed every relevant European law to become part of UK law; and (ii) providing that, if there was a conflict between UK and European law, European law would prevail, even if the conflicting UK law was newer. This was a legislative choice. Parliament can still repeal or amend the ECA to remove or loosen these restrictions. The result is that, like German law, UK law still has primacy over European law, and Parliament is still sovereign. These legal facts are often overlooked, but they are the result of R -v- Secretary of State for Transport ex parte Factortame Limited [1991]; Thoburn -v- Sunderland City Council [2003]; and section 18 of the European Union Act 2011.

That doesn’t necessarily mean that, if Parliament repealed or amended the ECA, its actions would be consequence free. If might, for example, breach European law. But Parliament could choose to cause the UK to breach European law, and then seek to defend itself from the  possible consequences of that breach (if any). Alternatively, the UK government could give two years’ written notice to the European Union, and walk away without breaching European law (if it thought that would generate a better result).

The legislative choices set out in the ECA are not only temporary – they’re also partial:

• There isn’t a European law about everything;
• When there is a European law, it doesn’t always apply in or to the UK;
• European law often includes derogations and implementation options, so the UK can chose whether to implement some European laws, and how to implement others; and
• European law is often “minimum harmonising“, so the UK can – and often does – require more from UK businesses than European law would otherwise have required.

It’s also worth remembering that new European law is sometimes based on existing UK law; and that, especially in the financial services regulatory space, the UK often plays a significant role in the development of the policy on which European law is based; and then “holds the pen” so that it controls the drafting as well. Although it’s not always happy to admit it these days, Solvency II is a recent example of almost all of these things. And the UK got many of the things it wanted in this way.

This seems to suggest that, as a matter of UK law, Parliament hasn’t given its sovereignty away after all.

If had, the next question might be: if there’s a #Brexit, would that be enough to allow Parliament to recover what it’s lost or given away, or at least to free itself from these “self-imposed” sovereignty restrictions? The answer, in every case, is that “it depends”. For example, the Norwegian option, and the Swiss option, are likely to involve making a similar set of revocable legislative choices to the choices Parliament has already made. In fact, Parliament is only really likely to be European Union sovereignty restriction free if it turns it back on the European Union altogether. But if it did that, it might still have to make other sovereignty restriction choices, as it entered into a series of trade agreements, bi-lateral treaties and other agreements with third countries; and that seems only to be a question of fact and degree.

[View source.]