The Court of Appeals at the Royal Courts of Justice in London ruled Friday that convictions against 15 protesters for a deportation flight protest in 2017 must be set aside.

The protesters, known as the “Stansted 15,” broke into the Stansted Airport in March 2017 to stop a plane chartered by the Home Office to deport about 60 people from UK detention centers to West Africa. The group surrounded the plane, connecting themselves with pipes and foam.

In December 2018, the individuals were convicted at the Crown Court at Chelmsford of “intentional disruption of services at an aerodrome,” under the Aviation and Maritime Security Act of 1990. In February 2019, three of the individuals were given suspended fail sentences. The others were given community orders.

The Court of Appeal found Friday that the protesters’ conduct did not fall within section 1(2)(b) of the Aviation and Maritime Security Act. At trial, the prosecution’s case was that the actions of the protesters presented “several real risks to the safe operation of the airport and those present,” which would satisfy the requirement that the protestors endangered or were likely to endanger safe airport operation or individual safety.

The court stated that the phrase “to disrupt the services of the aerodrome” insinuated that there needed to be more proof than limited interference with traffic movements. “[M]ere presence at the scene in possession of devices and substances which are not dangerous” fell short of that criteria. The protestors’ action did not endanger the safe operations of the aircraft, the aerodrome, or individuals. Because of this, their actions did not satisfy the criteria of the act.

The court concluded that the “Stansted 15” should not have been prosecuted under section 1(2)(b) of the act, and quashed the convictions.