Lord Sewel is the latest victim of British mob rule

Britain loves to pat itself on its back. We love due process and the rule of law. But if the last couple of days demonstrate anything, it's that we're as susceptible to mob rule as anywhere else. But instead of pitchforks we use grand phrases like 'bringing into disrepute' and 'undermining public confidence'. It adds up to the same thing. The rules and laws don't matter. What matters is whatever the press and the public demand.

This morning Lord Sewel quit the House of Lords. The pressure on him was immense. The police were battering down his front door, the prime minister was making critical statements, the radio airwaves were jammed with parliamentarians crawling over themselves to condemn him. He had been judged quite independently of any formal process.

Two reasons were given for why he had to go immediately rather than be investigated by the standards committee: that it would take too long and that they might not come to the conclusion everyone had already decided they had to come to.

One of the problems for Lord Sewel's critics was that neither the police investigation nor the standards committee report were likely to find against him. While he appeared to be taking cocaine in the video filmed of him with two sex workers, it would be very difficult to prove that to the required standard in a court of law. Sure, he makes some lame joke about Coca-Cola, but that's unlikely to be enough. Does it look like Lord Sewel may have broken the law? Certainly it does. But that is not how we judge people in this country. We ask whether they can be prosecuted in a court of law. That standard does not appear to have been reached in this case.

The standards committee was also unlikely to find against him. It really would only have been able to look at his behaviour in the House of Lords, which no-one seems to be complaining about. One could conclude from that that his professional conduct was not in question and therefore that it is none of our business what he gets up to in his leisure time. Instead, most of the serious people are debating whether they should add the catch-all 'bringing into disrepute' category to the Lords standards committee.

They can dress it up how they like, but this is the great circular self-fulfilling prophecy of mob rule. By the time these cases reach the standards committee, they are always being covered by the press. So it is always possible to say the individual has brought the House into disrepute. It is true by virtue of the investigation taking place at all. 'Bringing into disrepute' is the phrase we use to give subjective demands formal constitutional standing. It says that it's not what you do that counts, it's what people perceive you to have done.

So the police went to Lord Sewel's flat, with the press taking photos in the background, and battered his door down. But this wasn't enough for the puritans in the media.

The Mail reported that they "grudgingly shuffled into action" because it was "almost impossible to ignore his degrading activities". Notice how the moralising language of old creeps back into the daylight during these sorts of scandals.

Alas this moral puritanism does not extend to the only person entitled to be upset with the peer: his wife. At a deeply traumatic time, she was treated to the usual harassment by journalists. As the Mail reported:

"Lord Sewel's wife of ten years Lady Jennifer, was in their million pound house near Aberdeen today.

"A friend answered the door and told MailOnline: 'Lady Jennifer will not see you and she has no comment to make'.

"Asked if Lord Sewel was coming back she said: 'Lord Sewel is not here and is not expected'."

That's always how it goes with moral puritans. They act horrified in public, but when it comes to the only person who might legitimately have a claim to being let down by Lord Sewel, their only instinct is to make their lives even worse. Puritanism and compassion do not make good bedfellows.

Then out came David Cameron, lending his prime ministerial authority to the swelling outrage. "These are very serious allegations," he said. "I think it's right he has stood down from his committee posts and I'm sure further questions will be asked about whether it is appropriate to have someone legislating and acting in the House of Lords if they have genuinely behaved in this way."

Once the prime minister speaks about you like this it's hard, if not impossible, to get a fair hearing anywhere else, inside or outside parliament.

By this morning, Lord Sewel buckled. His statement said:

"The question of whether my behaviour breached the code of conduct is important, but essentially technical. The bigger questions are whether my behaviour is compatible with membership of the House of Lords and whether my continued membership would damage and undermine public confidence in the House of Lords. I believe the answer to both these questions means that I can best serve the House by leaving it."

Right there, embedded in his statement, is the same moral focus as in those who hounded him: the shifting sands of public opinion. For Lord Sewel it offers a chance at a dignified exit. He gets to claim that he is stepping down in order to preserve the institution he works for. It acts as a useful deflection from his own conduct. For his opponents, it gives sombre voice to mob rule.

Whether one has actually broken the law or the rules of the organisation which one works for is apparently immaterial. What matters is if you have angered the public mood. The great populist spasm of modern Britain demands blood. And this week it was Lord Sewel's blood it claimed.