On the first Thursday in May 2023, a man comes to his local polling station to vote. In his eighties, he never leaves his town, so he does not have a passport. He walks to the town centre, so he does not have a bus pass or a driving licence. He is not disabled, so he does not have a blue badge. He is aware enough of the new requirements to have brought a photograph with him to show ID, but he is not aware enough to use a computer or apply for a voter authority certificate. He is unable to vote for the first time in his adult life.

This year, England trialled voter ID on polling day for the first time, and it will have discouraged some people from voting. Figures from the Electoral Commission suggest around 14,000 tried to vote and were turned away. The real figure is likely higher as “greeters” outside the polling stations will have turned some people away before they could be included in the figures. The trial took place at the local elections, where turnout is under 50 per cent, and voters are already part of an engaged minority.

Criticism of the voter ID requirement has three major points: first, electoral fraud doesn’t happen; second, it wouldn’t matter if it did; and third, even if it does happen, voter ID puts an unacceptable barrier between vulnerable people and voting, like the gentleman in the story above. That third argument is a powerful one, but it also hinges on the first and second: if election results were decided by blatant and obvious box-stuffing in every election in every constituency, it would be obvious that the safeguard of requiring ID represents a net gain to democracy. No one really disputes the ID requirement for alcohol in supermarkets or to pick up post, because they remember breaking the rules as teenagers and are aware of the concept of theft.

Let us then begin with the first and second arguments: electoral fraud doesn’t happen, and it wouldn’t matter if it did.

Whilst the UK delivers democratic elections, this happens despite our system

There’s a joke about an economics professor on polling day: he pulls up in front of a polling station, gets out of his car, pulls his collar up around his neck and hat down over his eyes, and slinks into the polling booth. He leaves the building without making eye contact, but as he gets to his car, he bumps into a colleague. They both freeze. Thirty seconds of silence later, the first man says to the other, “Look. I won’t tell anyone we were here if you won’t.” The joke is about the relative impact of a vote: our two economics professors are embarrassed to be seen at the polling station because, from a purely individual, utilitarian perspective, bothering to vote does not make sense. The impact of the individual action is so small as to be insignificant, and all society shares in the positive or negative result regardless.

That is the theory. In 2017, though, Labour were five seats away from being able to form a “rainbow coalition” multi-party government led by Jeremy Corbyn. To have won those five seats, they would have needed less than 900 extra votes in the right places. Out of an electorate of 47 million people, history was, arguably, decided by less than 1,000. Two things can be true simultaneously: that the influence of the average vote is small, and that very small numbers of votes in the right places can have a lot of power. Under FPTP, votes have low average influence, but that contains significant variance. Someone voting in a seat with a majority of 32,000, in an election won by 80 seats, has comparatively little influence. Someone voting in a seat decided by 22 votes, in an election won by 13 seats, has a lot. Under FPTP, small numbers can matter.

That brings us to the first argument — the idea that electoral fraud doesn’t happen. In 2004 police officers entered a warehouse on an industrial estate. They found a group of men sitting around a table filling out ballot papers. Not experienced in election law, the police officers asked some questions before leaving the site, then returned to confiscate the ballot papers. What next? The police didn’t know, so later that morning, the papers were given to the team at the local Council responsible for running the election. The ballot papers were accepted, processed and counted as validly cast votes.

As electors in Britain, we don’t question that when voting takes place the declared result is accurate. In 2008, a Council of Europe assessment found British procedures “open to electoral fraud … mainly the result of the, rather arcane, system of voter registration without personal identifiers”. It concluded that whilst the UK delivers democratic elections, this happens despite our system. Our history of democracy is a strength and a weakness: our system has gradually evolved so we’ve carried anachronisms with us. Some stand the test of time: the 1883 election offence of undue spiritual influence, telling an elector that it is their religious duty to vote a particular way, came onto the statute books as a response to Irish Home Rule. It was last tested in court in 2015. This history also means we can fail on the basics, however, like ID or abuse of postal votes, or the creation of “ghost voters” by registering real electors at the wrong address.

It is rare that the police know what to do or have the capacity to handle election law

On ID, we are an outlier. Across Europe — in France, Finland, Germany, Greece, Hungary, Iceland, Italy — the norm is either that ID is compulsory or can be requested. In Northern Ireland, it’s been a requirement since 2002. Electoral fraud is a self-fulfilling prophecy. Our system makes it difficult to prevent. The same weaknesses make it difficult to report, which makes it difficult to challenge, difficult to prove and, as a result, difficult to fix. The dramatic examples of stolen elections — Birmingham in 2004, Slough in 2008, Tower Hamlets 2015 — got to court thanks to the courage of individuals. If the law is broken, there is no clear responsible body. To bring a case of election fraud requires a member of the public to make a petition, at substantial financial risk to themselves.

In theory, breaches of election law are the responsibility of the police. As the 2004 example shows, it is rare that they know what to do or have the capacity to handle election law as priority. That year, complaints of electoral malpractice were given the codename “Operation Gripe”. The most knowledgeable public servant involved in elections is the local Council’s Returning Officer — but they must accept what they are given or told at face value.

Reviewing the arguments against voter ID, the numbers show that it matters; the case record shows that it happens. The only argument that remains is that of barrier to participation. Looking at the cases of stolen elections, what they have in common is where they frequently happen: within the UK’s most deprived communities. It is inexcusable to suggest that because large-scale electoral fraud does not happen in leafy suburbs, it should not be dealt with; inexcusable to suggest that bringing a driving licence to the polling station is too much to ask to secure the integrity of the ballot in Tower Hamlets. As always when the law breaks down, the most vulnerable are the victims. It is because everyone’s vote matters that the safeguards of ID are so important.