Protesters who damaged a genetically modified crop claim the case against them was dropped because prosecutors knew a jury would be sympathetic.
The two campaigners appeared on Tuesday before magistrates in Colchester, Essex, where the Crown Prosecution Service (CPS) said criminal damage charges had been discontinued.
Andy Abbott, 33, from Colchester, said the dropped case showed that authorities had given up trying to prosecute GM protesters.
"The government is giving a green light to people to trash GM crops," he said.
Insufficient evidence
A CPS spokesman said: "Once we looked at the evidence we decided there wasn't sufficient evidence for a realistic prospect of conviction and we have therefore discontinued the case.
"However it doesn't mean that in future prosecutions over attacks on GM crops will be discontinued."
Mr Abbott and Jack Upton, 21, also from Colchester, handed themselves in to police after two acres of the GM maize was damaged at Wivenhoe, Essex, last year.
A Greenpeace spokesman said: "People are still getting off with this but the government is still pushing ahead with GM crops - the resistance is there but the government doesn't realise that."
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