Nora Ziegler, Chris Cole, Jo Frew, and Henrietta Cullinan shackled themselves together and lay in the middle of the road outside the ExCeL centre in September 2017.
The Supreme Court on Friday said the four could have relied on a human rights defence at their trial, in a ruling which could have widespread ramifications for protestors and authorities trying to break up blockades.
In a summary of the ruling, the judges found that courts should consider if the breaking-up of protests was “proportionate”.
“If it was not proportionate, such that the interference was unlawful, the protestor will have a statutory defence of lawful excuse.”
A District Judge at Stratford magistrates court found the defendants not guilty of willful obstruction of the highway in February 2018, deciding they were exercising their rights to free speech and assembly.
The High Court replaced the acquittals with convictions, following an appeal by prosecutors, but the Supreme Court overturned that decision.
Raj Chada, a partner at Hodge Jones & Allen who represented the protestors, said: "We are delighted that the Supreme Court has recognised that protests which are deliberately obstructive are still protected under Article 10 and 11 of the European Convention on Human Rights.
“Disruptive protests can and do change things. From anti-apartheid campaigners stopping sports events to civil rights protestors conducting sit ins, disruption as a form of free speech can be the spark for radical change.”
A trial of six Extinction Rebellion protestors over a blockade of newspaper deliveries was halted last week to wait for the outcome of today’s case.
Judge Sally Fudge, at St Albans magistrates court, accepted: “All trials in this case, where possible, should be determined under the same law. And, what happens in this trial has and will have an impact on the following trials.”
The Supreme Court decision could have ramifications for other trials of XR protests which are waiting to be heard.
The issue of the right to protest is currently under consideration in Parliament, as the government attempts to bringing in further police powers to curb protests through the Police and Crime Sentencing Bill.