Mark Steel: How to take on an arms manufacturer – and win

A trial took place recently in Belfast that seems to explain how nothing makes any sense. It revolved around a factory owned by the arms company Raytheon, which was set up in Derry soon after the IRA ceasefire. John Hume, who'd just won the Nobel Peace Prize, was among those who announced the opening of the plant, welcoming it as a result of the "peace dividend".

So now the men of violence had agreed to give up their weapons, the area could attract a peaceful company with a turnover of $17bn from making weapons, announced by a man with a prize for bringing peace.

Clearly, while the IRA were decommissioning their arms, most of us misunderstood this process. Because the government reports must have gone, "They possess 100 rifles, 10 RPGs, 7 rockets and a shed full of Semtex. If they want to be taken seriously this isn't nearly enough; they need Tornado bombers and a car park full of tanks – we can't deal with these amateurs."

For example, when Raytheon won a contract to develop a new missile system for the Israelis in 2006, a spokesman boasted they would, "provide all-weather hit-to-kill performance at a tactical missile price". Next they might have adverts that go, "Hurry hurry hurry to the Raytheon springtime sale for lasers, Tasers and civilian-erasers. We'll make flesh sizzle through snow, sleet or drizzle, and without making a casualty of your wallet".

Despite this, the government in Northern Ireland welcomed the new plant, claiming they'd been assured it wouldn't be making weapons. To which a reasonable response would be, "Right – they're a weapons manufacturer. They supplied weapons to, among others, the Indonesian military junta. This might, if you were cynical, suggest they make weapons. Or what do you think they're going to be making – Fairtrade poxy custard!"

Eventually it was admitted that they were developing software for guiding missiles, and so for a while there was a pretence these were being employed for peaceful reasons. Perhaps the systems were being attached to wasps so they could be guided away from picnics.

But then it became clear that they were being used by the Israelis in Lebanon, and one such system guided a missile into a block of flats in Qana, killing 28 people, mostly children. A few days later the local anti-war group, including the journalist and civil rights activist Eamonn McCann, decided to occupy the Raytheon building as a protest. A group of nine got into the plant, and as a gesture they threw a computer or two out of the window.

Eventually around 40 police arrived and, as Eamonn describes, "They smashed through the doors wearing riot gear, many holding perspex shields, some pointing plastic-bullet guns. They inched forward while the officer in command shouted 'Surrender!'. We continued playing cards." And you can imagine this catching on, eventually being shown every night on the Men and Motors channel as Extreme Rummy.

Then came the official outrage – they'd wilfully broken the law, destroyed property etc, etc. So maybe whether an act of destruction is considered illegal or not comes down to the value of the objects destroyed. And computers are worth a fair packet, whereas a house in Qana can probably be picked up for next to nothing, especially with the current housing slump!

Perhaps the activists irritated the authorities by bothering to find out whether Raytheon was actually making these weapons. A more official approach might have been to announce that the local Co-op was making weapons, as proved in a dossier containing snippets from the internet about how the manager had been buying uranium from North Korea and smuggling it in packets of fish fingers, and flatten them instead.

Last year the group travelled to Qana to meet the families of the victims of that missile, and they described the trip, not surprisingly, as the most moving experience of their lives. But while it's all very well feeling compassion for dead civilians, someone has to consider the feelings of those poor computers, so the nine went on trial in Belfast.

But then the case revolved around whether the defendants "held a genuine belief, with reasonable evidence, that their actions were preventing war crimes by Israel". If this could be proved, then it would be established that they acted to curtail a greater crime, and they'd be found innocent. So that's what the jury did and they were free to go. The outcome was so remarkable, you almost dare to imagine a day when Blair and Bush are in a cell with Karadzic, arguing about whose turn it is to slop out.

But mostly, I wonder if, when the computers hit the ground, in their last moments they flickered, "You have performed an illegal operation".