Gail Bradbrook, the co-founder of Extinction Rebellion (XR), has been found guilty of causing £27,500 worth of damage to the Department for Transport in 2019 after a four-year legal battle over protest rights.
Bradbrook climbed onto an entrance canopy at the department's headquarters during a major XR protest in October 2019 and used tools to break a large pane of reinforced security glass.
She argued that her actions were necessary to prevent greater crimes against the environment, but the judge ruled that her arguments were not valid legal defenses.
Bradbrook will be sentenced on 18 December, with a suspended sentence as a potential option. In a separate case, she has also been convicted of breaking the window of a bank.