Life in the Faslane

The Green MEP on her arrest during a protest at the Trident base

What's more likely to cause a breach of the peace - sitting down in a road, or stockpiling 200 nuclear warheads, each with a destructive capacity eight times greater than the bomb that killed 200,000 in Hiroshima?

If, after careful consideration, you conclude that the first use of Her Majesty's highways is a less serious threat to national and global security, I'd be grateful if you could drop a line to the Procurator Fiscal in Glasgow. For this is a matter that he, as the local prosecutor, is likely to consider increasingly as more and more of us join peaceful blockades of the Trident nuclear submarine base at Faslane in Scotland, part of a year-long non-violent protest, with a different group taking part each day until October.

On Monday it was the turn of a group of politicians, and I whiled away six long hours in a freezing cold cell in Clydesdale Police Station, having been arrested, along with eight others, and charged with taking action likely to cause a breach of the peace. Legal precedent has it that breach of the peace requires conduct severe enough to cause alarm to ordinary people. But, to most of us, what is more alarming is the government's determination not only to retain Britain's nuclear arsenal but to upgrade it.

No one can know what enemy our weapons would be aimed at, nor from where a threat to our security might come. The 2006 Commons defence committee inquiry, looking into the context of Trident replacement, concluded: "The most pressing threat currently facing the UK is that of international terrorism. Witnesses to our inquiry overwhelmingly argued that the strategic nuclear deterrent could serve no useful or practical purpose in countering this kind of threat."

Instead, government ministers fall back on the argument that nuclear weapons represent an "insurance policy" for the future. Yet the truth is that, rather than providing insurance against an unspecified threat, replacing Trident will increase the danger of nuclear proliferation.

Trident is irrelevant to the real security threats that we face, and ridiculously expensive. Recent estimates suggest the total bill, including maintenance, will be £76bn over 30 years. For that price, we could invest in the energy-efficient technologies we urgently need to tackle the greater threat we face from climate change.

By the time the Procurator Fiscal has heard these arguments for the thousandth time, he might be minded to agree that a minor trespass on a Scottish byway is of relatively little importance by comparison.

Caroline Lucas is Green Party MEP for South-East England

Caroline Lucas is the MP for Brighton Pavilion.