The aid workers, who were facing up to eight years in prison if found guilty, included Sara Mardini, a Syrian featured alongside her Olympian sister in the movie “The Swimmers.” Her involvement raised the profile of the case and the international it received.
The case had been decried by the United Nations’ human rights office, as well as other groups monitoring migration to Europe.
“This case is a textbook example of how the criminal justice system can be misused by the authorities to punish and deter the work of human rights defenders,” Amnesty International said in a statement Friday after the court decision.
Mardini, along with Irish aid worker Sean Binder, had been jailed for several months after their arrests in 2018. They had been working at the time in Lesbos, a main landing point for undocumented migrants trying to cross by sea from Turkey. Both are still under investigation for felony charges, including human trafficking.
“Today’s outcome undermines the legal basis” for future charges, defense lawyer Evita Papakyriakidou said.
Zacharias Kesses, another defense lawyer, said the 24 defendants largely had been working for small NGOs, and that “looking at the sea through a pair of binoculars is not enough to build an espionage case.”
The Greek government did not immediately comment on the court decision.
For several years, under a conservative government, Greece has been working to tighten its doors to undocumented migrants. Part of the response, supported by widespread documentation but denied by Greek authorities, involves dragging migrant vessels back to international waters, in violation of maritime law — a practice known as pushbacks.
Even though migration to Europe has hit its highest level since 2017, Greece last year saw only 12,700 arrivals by sea. In 2016 and 2015, the height of the migrant crisis, it saw more than 1 million people come to shore, many of them escaping Syria and other conflict areas.
That spike helped to brew resentments in Europe’s front-line Mediterranean countries, especially as other European Union members resisted attempts to divvy up asylum seekers.
Beyond the trial in Lesbos, Greece has brought charges against the heads of several other groups involved in migrant work. And Italy has tried to crack down against humanitarian rescue vessels that patrol the Mediterranean, impounding some boats, and at one point arresting a captain who navigated to an Italian port against government orders.