A federal judge on Tuesday vacated the 2017 court martial conviction of Bowe Bergdahl, a US soldier held by Taliban forces after leaving his post in Afghanistan who was later released in a prisoner swap.
Judge Reggie Walton, in a ruling seen by AFP, said that Bergdahl's case had been tainted by a possible conflict of interest as the military officer presiding over the suit had not disclosed his attempts to be hired by the administration of then-president Donald Trump.
During the 2016 presidential campaign, Trump repeatedly suggested Bergdahl should be executed, and after winning the election promised to review the case, labeling him a "dirty rotten traitor."
Bergdahl, 31 at the time of his conviction, did not receive prison time, but was sentenced to a dishonorable discharge, with his rank slashed from sergeant to private and forced to pay a $10,000 fine.
Trump blasted that limited sentence as "a complete and total disgrace to our Country and to our Military."
Bergdahl had faced up to life in prison after pleading guilty to charges of desertion and endangering his fellow troops when he abandoned his unit at a small camp in eastern Afghanistan in 2009.
He was captured shortly thereafter by the Taliban and turned over to the notorious Haqqani group, which held him for five years in nearby Pakistan.
He was freed in a 2014 exchange for five Taliban fighters, a deal that brought strong criticism of then-president Barack Obama.
Bergdahl's lawyers had tried several times to have the charges against him thrown out, saying comments by Trump in favor of a heavy prison sentence constituted "unlawful command influence" -- when senior officials with power over the military exert potentially prejudicial influence over the court.
The case put a focus on the strains that the lengthy conflict in Afghanistan had placed on US armed forces.
Detractors labeled Bergdahl a turncoat whose actions caused fellow soldiers in his unit to be severely injured.
But supporters consider him a victim of the war.
Bergdahl said he had left his post in 2009 to walk through the Taliban-filled, eastern Afghan countryside to a larger US base to report command problems in his unit.
Bergdahl's lawyer Eugene Fidell told AFP that the legal team "is studying Judge Walton's important decision."
"No decision has been made as to future steps at this time but we believe this was a very good day for the rule of law in our country," he said.