The charge arose from an action by Greenpeace when we tried to remove a crop of genetically modified maize from a field near Lyng. The prosecution alleged that it was a stunt. We proved we acted lawfully in defence of property. The crop was about to flower, threatening cross-pollination of neighbouring crops. Once such genetic pollution escaped, it could not be recalled. We aimed to cut down and bag up the entire field and return it to Aventis, the agrochemical company that owned the crop.

Greenpeace Executive Director Lord Melchett is surrounded by supporters on September 20, 2000 after the Greenpeace 28 were cleared of causing criminal damage by destroying GM crops Photograph: STEFAN ROUSSEAU

The owner of the field had refused to meet his neighbours to discuss whether they wanted GM crops in the vicinity. He and the chemical company decided simply to impose the contamination on them. The real victims of this episode are the local farmers who may not be able to sell crops contaminated by GM.

Genetic engineering is a complex issue, probably the most complex and certainly one of the most serious Greenpeace has ever grappled with. But what has been the response of the liberal media and London salon society which have promoted deliberative democracy with such fervour? Shocked indignation that the jurors have had the temerity to challenge what they assumed to be scientific certitude.

There seem to be two key objections to what we did: that we seemed to challenge the need for scientific progress; and we took direct action. The Government tells us the farm-scale trials will show whether GM crops pose a threat to human health or the environment. This is just not true - the trials are not about human health at all, even though the Government claims that they are. Nor are they about whether GM crops will contaminate non-GM ones; the Government and its scientific experts long ago accepted that contamination is inevitable, but think it does not matter.

Nor are they about whether GM crops will pollute the soil they grow in. They are simply about whether farmers growing GM crops will use more or less weedkiller, a question which could have been answered by looking at the experience of GM crop cultivation in North America. We know that the answer is mixed - sometimes more chemicals are used, sometimes less.

We do not need GM crops to reduce our dependence on chemical weedkillers - we need research into fulfilling the potential of organic farming. The farm scale trials aim to establish something we do not need to know, at a risk of irreparable damage to the environment. To oppose them is not to be anti-science, but simply to recognise that there are some things which cannot be justified in the name of science.

And what of direct action? I believe it is a legitimate tactic, but only in some forms and in clearly defined circumstances. First and most important, it must be non-violent. Second, it should be used only after other avenues have been explored. Third, it should be in defence of a clear moral principle, not an attempt to impose the economic self-interest of a particular group on the rest of society. Fourth, it should be to prevent a real and immediate threat, such as genetic pollution.

Greenpeace disagrees with the aims of those who blockaded refineries - the true cost of petrol and diesel, taking account of climate change and damage to human health, is far higher than the price we pay at the pumps - and with their methods. It was a clearly implied threat and self-interested, motivated by issues often unrelated to transport.

There is another important point about Greenpeace's involvement in direct action. We do not conceal our identities or evade arrest. We challenge particular laws, but not the rule of law. We take responsibility for our actions and are happy to be judged, fairly, for them.

© Guardian Newspapers Limited 2000

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