The Hillerod District Court in Denmark has rejected an Indian extradition request in the trial of Danish citizen Niels Holck.
Indian authorities allege the 62-year-old is a terrorist who supplied West Bengali rebels with arms to fight government troops in 1995.
The court, which was solely ruling on whether to extradite, and not over guilt or innocence in the case, said that to deliver Holck would violate Denmark's extradition act due to a risk that he would be subjected to treatment in breach of the European Convention on Human Rights.
"The guarantees India has provided are not valid," said defense lawyer Jonas Christoffersen.
Prosecutors now have three days to appeal the decision.
Only one to escape capture
Holck has previously admitted to parachuting four tons of weapons to West Bengalis whom he said needed them to defend against local communist authorities.
Holck was the only passenger to escape from a Russian cargo plane delivering the arms from Bulgaria when it was intercepted by the Indian air force.
Six other European nationals were captured, tried, jailed and later released. New Delhi claims Holck, who was known by his alias Kim Davy at the time, was the plan's mastermind. Holck managed to escape to Nepal and then Denmark in 1996.
India desperately wants Holck to stand trial, promising to build a new detention facility for him alone and allowing Danish police to accompany as observers. The court, however, said that his safety could not be guaranteed despite New Delhi's promises.
Holck was arrested in 2010, when Danish officials struck a deal with India over extradition — including guarantees that he would not be put to death and that he would be able to serve any sentence handed down in a Danish rather than an Indian jail.
The decision was overturned by a Danish district court in 2011, over fear of mistreatment. The ruling was upheld by an appeals court later that year.
India again requested Holck's extradition in 2016.
The case has strained Danish-Indian relations for years.
Defense hopes accused can get on with his life
Holck's lawyer Jonas Christoffersen said he was "very satisfied with the decision" but expects the prosecution to appeal yet again.
Still, he voiced confidence that the Danish court system would protect Holck after three separate rulings in his favor.
"We would be very surprised to say the least, if the High Court would reach another conclusion this time," said Christoffersen.
"Now," the defense lawyer continued, "he's hopeful that it will come to a close and that once it has gone through the Danish legal system, it will be clear that he will never be extradited to India."
"He is going on with his life, but he cannot travel. He has his life in Denmark but it's a burden on him," Christoffersen said of Holck. "He's been called a terrorist without any factual merit for 28 years."