Trespassers can be prosecuted despite what they believe, the Supreme Court says.

A little learning is a dangerous thing, wrote Alexander Pope in 1709. Most lawyers are familiar with the sort of client who insists that trespassers cannot be prosecuted. This month, the Supreme Court put two of them right.

On 2 October 2010, Matthew Richardson, 24, and Gwen Wilkinson, 20, both unemployed, entered a shop selling beauty products in Covent Garden, London. They were there not to buy from its extensive range of face creams but to prevent the shop from serving anyone else. With a little help from their friends, the two protesters placed a heavy concrete tube on the floor and padlocked their arms through it. The police were called; the shop was closed; the concrete was broken; and the two of them were arrested.

Richardson and Wilkinson were charged with aggravated trespass under section 68 of the Criminal Justice and Public Order Act 1994. This makes it an offence to trespass on land if the trespasser intimidates others from engaging in lawful activity there; or if he obstructs or disrupts that activity. Activity is lawful if it is not an offence.

There is no doubt that Richardson and Wilkinson were trespassers: they failed to leave the shop when asked. There was no doubt that they were disrupting the shop’s activity. But, they argued, the shop’s activity was not lawful. They said that gave them a defence.

Not so, said the district judge in 2011. Not so, agreed the divisional court, ruling in 2012 on an appeal by way of case stated. And not so, agreed the Supreme Court in 2014, unanimously upholding their criminal convictions.

Giving judgment, Lord Hughes dealt with the trespassers’ claim that those running the shop had been guilty of a criminal offence. First, he explained, not every offence would render a shop’s activity unlawful for the purposes of aggravated trespass. It was no defence to claim, for example, that a worker at the shop was paid less than the national minimum wage. The criminal offence must be integral to the shop’s core activity rather than collateral to it or remote from it.

Hughes then turned to four specific arguments put forward by Richardson and Wilkinson. The UK company running the shop, Ahava UK, was a subsidiary of an Israeli manufacturing company called Ahava Dead Sea Laboratories. That company produced products for sale at the shop at its factory in the West Bank, situated in what the court referred to as occupied Palestinian territory.

Since there were Israelis working at the factory who had been encouraged by their government to live in the West Bank, the UK company running the shop was – according to the trespassers – guilty of assisting an occupying power to transfer parts of its civilian population into territory it occupied. This would be a war crime under the International Criminal Court Act 2001.

Hughes gave those arguments short shrift. First, the UK company was not involved in manufacturing. Second, it was ‘very doubtful’ that the manufacturing company was encouraging or assisting the Israeli government in an unlawful transfer of its population. But, in any case, assisting in any population transfer was not an integral part of the shop’s activity, which was retail selling. That selling was ‘perfectly lawful’, Hughes said.

His conclusion also defeated the trespassers’ second argument, which was that the shop was guilty of money laundering because items sold in the shop were the product of assisting in a war crime.

The trespassers’ third argument was that the company was guilty of cheating Revenue & Customs by importing products under a favourable tax regime that did not apply to the West Bank. But there was no evidence of this, the judge said, and in any case it would have been merely collateral.

Finally, claimed the trespassers, the shop’s products bore labels saying they were made at the ‘Dead Sea, Israel’. Trading regulations made it an offence to provide deceptive or false information that was likely ‘to cause the average consumer to take a transactional decision he would not have taken otherwise’.

That argument came closest to the store’s core activity, Hughes acknowledged. But the district judge had concluded, in effect, that most shoppers would either buy all Israeli goods or none; the ‘average consumer’ would not buy goods made within Israel’s pre-1967 borders, while choosing not to buy those made in areas it has administered since the Six-Day War.

It seems hard to believe that even a non-lawyer would think a disruptive sit-in could become lawful because of events that were not integral to activities at the occupied premises. Otherwise, where would it end? Richardson and Wilkinson now have criminal records. And for what? Two years of demonstrations and counter-demonstrations outside its Covent Garden shop were enough to persuade Ahava to close it in 2011.