Mr Nick Jones, an Irish environmental activist detained in Ecuador last week, was released from prison on Monday.
He is expected to arrive in Dublin today after local authorities dropped all charges against him.
Mr Jones and 17 others were arrested and imprisoned in Quito, the nation's capital, on March 25th after peacefully protesting against the construction of an oil pipeline through the Ecuadoran Amazon rainforest.
The protesters were accused of causing criminal damage at the site of their tree camp.
Several protesters were released and deported, but Mr Jones filed a habeas corpus writ which challenged the arrest and deportation orders.
"The oil company failed to show in court," explained Ms Alicia Poapanta, a legal aide who attended the court hearing.
"Hundreds of protesters arrived instead."
The local mayor, who ordered the detention of the activists, opted not to proceed with the case and released all detainees, including five Ecuadorans.
Mr Jones had spent the past month participating in a peaceful tree-sitting camp with a local group Accion Por La Vida (Action for Life) and the Mindo indigenous people in southern Ecuador.
The peace camp was set up to prevent construction work by Occidental Petroleum's (OCP) oil pipeline through the most sensitive area of the Mindo-Nambillo Protected Forest.
Dozens of local people blocked the main highway last week after the arrests and about 200 protesters turned up outside the court on Monday, pledging to maintain their action until all protesters were released.
Ms Molly Brown, international spokeswoman for Accion Por La Vida, denounced the criminalisation of the protest and vowed to continue the protests.
"The only government response to those opposing the pipeline has been through violent repression, illegally arresting the activists, putting them in jail without any legal basis and treating them like common criminals," she said.