We are on our way to a very dark place

I don’t agree with you, so I’ll see you in court.

Alternatively, I don’t agree with you so I’m going to expel you.

If your name is either Boris Johnson or Alastair Campbell, you’ll recognise the sentiments, because this week both have been on the receiving end of what I suppose we could call (if we must) political justicisation.

What it means – and yes, I did just make it up, so I hope you’ll forgive me – is converting a disagreement over politics into a case to be resolved judicially. In Johnson’s case, by bringing a case against him over his claim during the EU referendum campaign that the UK sends £350 million a week to the European Union. And in Campbell’s case by expelling him from the Labour party because he admitted – after the event – to having voted for the Lib Dems in last week’s European parliament elections.

It is an unhealthy trend and it leads, eventually, to a very dark place. Countries in which you are sanctioned for your political views are the very opposite of democracies, and the UK should be steering well clear.

One of the many reasons why the Brexit debate is doing so much damage to British political life is that it is dangerously coarsening the language of disagreement. Take a formerly respected figure like Andrew Adonis, whose CV includes a spell as an academic at Oxford university, a journalist on the Financial Times, head of the policy unit at 10 Downing Street under Tony Blair, and then transport secretary under Gordon Brown.

Now, he has become so unhinged by Brexit that he has suggested, apparently in all seriousness, that the BBC should be ‘in the dock’ together with Boris Johnson because it dared to report his referendum campaign claims.

Did Boris Johnson lie about how much the UK pays to the EU each week? Yes, he did. Should that render him liable to prosecution? No. Should the BBC be prosecuted for having reported what he said? Of course not.

In the words of the historian Robert Saunders, of Queen Mary University, London: ‘The court in which Boris Johnson should be found guilty is the court of public opinion. The sentence should be that he is voted out of his seat.’

The essence of democracy is the free exchange of ideas. According to Article 10 of the Human Rights Act: ‘Everyone has the right to freedom of expression. This right shall include freedom to hold opinions and to receive and impart information and ideas without interference by public authority.’

(The main exceptions are for the protection of national security, territorial integrity or public safety, the prevention of disorder or crime, the protection of health or morals, and the protection of the reputation or rights of others.)

It is not against the law to lie. It is, however, against the law to incite violence or racial hatred. It shouldn’t be too difficult to tell the difference – so much as I dislike what Boris Johnson stands for, I very much hope that the absurd private prosecution that has been brought against him will soon run into the judicial sands, never to resurface.

The Alastair Campbell case is different, but the principle is the same: in a democracy, no one should be sanctioned because their politics are not the same as yours.

Yes, the Labour party rulebook says (Chapter 2, Clause 1.4B): ‘A member of the party who … supports any candidate who stands against an official Labour candidate … shall automatically be ineligible to be or remain a party member.’

Tell that to the thousands of Labour party members who campaigned – and voted – for Ken Livingstone when he was running to be mayor of London in 2000 against the official Labour party candidate, Frank Dobson. None of them was expelled.

Or tell the backbench Labour MP who in 2012 congratulated George Galloway, then of the Respect party, for having beaten the Labour candidate in the Bradford West by-election. (The MP’s name, by the way, was Jeremy Corbyn. He wasn’t expelled either.)

According to the polling organisation YouGov, more than forty per cent of Labour party members voted for another party last week, lending their support more or less equally to the Greens and the Lib Dems. About ten per cent of them said they didn't vote at all, which leaves something like 185,000 who, if you really want to enforce the letter of the rulebook, should now be thrown out. 

No wonder the shadow attorney general Shami Chakrabarti now says that the decision to expel Alastair Campbell should be reviewed. Speaking to the BBC, she said: ‘Merely voting for another party is not in itself a grounds for exclusion or expulsion or anything like that, and I want the large numbers of people who did that last week for heartfelt reasons to rest assured.’

The figures for the Conservative party, by the way, are even more eye-popping. More than two-thirds of Tory party members voted for a party other than their own, the vast majority choosing the Brexit party.

It is, of course, intensely frustrating when people whose politics differ from yours say things that you know to be untrue. But in a democracy, the law must never be used to criminalise a difference of opinion.

The test for democrats is to find an effective way to combat the lies – and the deeply worrying fact about the Brexit crisis is that we have learnt the hard way that lies can often be much more powerful than truth.

If we are going to be put through the agony of another Brexit referendum or an early general election – which I think becomes more likely with every passing day – then it’s a test we shall probably have to pass much sooner than we might like.