R (Wilson) v Prime Minister [2019] EWCA Civ 304 is a UK constitutional law case, involving judicial review of the Brexit referendum in 2016.

These included, first, the findings of the Electoral Commission that "Vote Leave" officials were guilty of criminal offences for overspending nearly £450,000,[1] second, the Information Commissioner Office criminal penalty against Facebook for enabling unlawful appropriation of UK voters' personal data and use in targeted political advertising,[2] and third, the conclusion of the House of Commons Digital, Culture, Media and Sport Committee on ‘Fake News’ that Russia had engaged in "unconventional warfare" through social media to manipulate UK voters.

[3] It was also submitted that it was relevant that the National Crime Agency was investigating Arron Banks, the largest donor to Brexit, for being unable to show that his donation came from UK sources.

It followed that the decision by the prime minister, Theresa May, to notify the EU of the intention to leave was based on a flawed premise that the referendum could be said to reflect the "will of the people".

Ouseley J held that the claim was unduly delayed, and further added that the basis for judicial review lacked "merit".

The Court of Appeal decision in Morgan v Simpson, where Lord Denning MR held that votes must be declared void if they substantially violate the law, "relies on quite old cases" and "none of which deal with a referendum".

The Venice Commission requirements for a fair question in a referendum and the European Convention on Human Rights added "nothing in this context".

On 20 March 2018 counsel for the DCMS Committee provided a legal opinion which in para.176 referred to strong evidence of offences being committed by the Leave campaign under the PPERA.

On 27 March 2018, there was a debate in the House of Commons about the alleged breach of electoral law in the referendum which included reference to four hours of testimony which had previously been given before the Digital, Culture, Media and Sport Committee talking of clear evidence of systemic law breaking by Vote Leave and others; the Government response was to say that the Electoral Commission’s conclusions had to be awaited before anything was concluded.

The evidence they did produce, cursory and patchy as it was, shows that there was widespread knowledge of the issue well before three months before they began these proceedings.

The claimants contend that there was no undue delay because they had to wait until the Electoral Commission reports were produced before they had a case which would not be thrown out at the very outset.

The rules in relation to undue delay may mean that some acts of public authorities are put beyond legal challenge anyway, and it is the consequential criminal or civil proceedings alone which can be pursued.

I emphasise that time does not begin to run from the moment of the discovery of what the claimants regard as sufficient evidence to proceed.

The fact that the statutory challenge grounds are limited to ballots counted and votes cast does not necessarily and unarguably of itself lead to the conclusion that the common law is excluded in all respects.

However, whatever the arguable role of the common law might be, I consider it hugely improbable, to the extent of being unarguable, that the common law would in those circumstances operate so as to void a referendum on the basis upon which the RPA would void a constituency election, even if the electoral offences are equivalent to corrupt and illegal practices which under the RPA would have had that effect.

And it is obvious that the common law developed in relation to constituency or ward based elections is inapplicable without adjustment to a nationwide referendum.

Moohan v The Lord Advocate [2014] UKSC 67, [2015] AC 901 concerned the right of prisoners to vote in the Scottish independence referendum.

But, in my judgment, were the common law to have a role to play in relation to avoiding elections or referenda because of an absence of statutory provision, the common law would require there to be some effect upon the outcome of the referendum no less demanding than, by way of example, soundly based grounds for believing that the outcome would have been different had the illegal acts not taken place.

This is a very difficult and contentious task which could itself reinforce the view that the common law did not intervene in these circumstances, leaving it to Parliament to evaluate all that in deciding what to do.