07/11/2016 06:57 GMT | Updated 08/11/2017 05:12 GMT

Brexit And The Bill Of Rights

In recent weeks, the 1689 Bill of Rights has often been invoked in political discussion. As a historian of the long eighteenth century, I have found it fascinating to see how the constitutional settlements of this distant period still have relevance today.

The ruling in the High Court yesterday confirmed that Parliament will have to vote in order to trigger Article 50, which would begin the process of leaving the EU. The judges rejected the government's case that it could use its existing executive powers to do this, and therefore start the negotiations with the EU without a parliamentary vote.

Pro-EU campaigners are claiming this as a victory, not least because most MPs are thought to favour remaining in the EU and this presents an obstacle in the way of the government's Brexit strategy. For these same reasons, pro-Brexit campaigners and newspapers have condemned the decision, suggesting that this ignores the will of the people as expressed in the referendum.

Wherever you stand on the EU, however, the case hinges on some fundamental constitutional issues. Is parliament sovereign? What is the extent of the government's executive powers? Can decisions that affect the rights of Britons be taken without parliamentary approval? Can the courts over-rule the government?

This is where the Bill of Rights is so crucial. Unlike most other countries, Britain has no single written constitution that sets out its citizens' rights and its political processes. The British constitution is instead the sum total of centuries of legal precedents, political practice and constitutional settlements, such as the Magna Carta or the Act of Settlement. Precisely how you interpret all these is up for debate - which is why it took a court case to decide the present issue (and why it will doubtless be appealed).

Constitutional precedents were repeatedly invoked in the court case. In particular, the judgement cited section 1 of the Bill of Rights: 'That the pretended power of suspending of laws or the execution of laws by regall authority without consent of Parlyament is illegall.' This essentially means that the government cannot alter laws by using its prerogative powers, and that it requires the consent of parliament to do so.

To understand where this principle comes from, we have to look at the political context of 1688-89. James II had been on the throne but his Catholicism posed a threat to the Protestant establishment. The Whig Party in parliament therefore negotiated with William of Orange to replace him. In this situation, parliament asserted its authority, and the Bill of Rights placed new restrictions on the power of the monarch, protecting the rights of parliament and the citizenry. This ensured that prerogative power could not be used in the way that James II had sought to use it.

Throughout the century that followed, this 'Glorious Revolution' was revered by Englishmen as the settlement that secured their liberties. When John Wilkes challenged the government to defend civil liberties and election rights in the 1760s, he was financially supported by the Society for the Supporters of the Bill of Rights. (Indeed, there are many parallels between Wilkes's landmark court cases and the present one: not least as the SSBR supported him on the crowd-funding model, not unlike the People's Challenge.)

However you feel about yesterday's verdict with respect to Brexit, it is important to recognise that wider political issues are at stake here. Pro-Brexit campaigners cannot claim to uphold the primacy of UK law and the UK's parliament, yet complain when they are inconvenient to their cause. Due process has to be followed, since the constitution protects the very rights that they are keen to preserve.

In Britain, if you want to understand the constitution, you need to know your history.