Calls to release a former Plymouth-based Royal Marine, and quash his conviction for murdering an injured Afghan fighter, could be debated in Parliament.
More than 100,000 people have signed an e-petition asking for Sergeant Alexander Blackman from Taunton to be freed and to have his murder conviction rescinded as he "defended his country from a terrorist".
This means it has exceeded the threshold required for it to have a chance of being considered by the Backbench Business Committee, which decides the issues debated in Commons time allocated to backbench MPs.
The committee meets weekly to consider requests for debate, although an MP must make a representation before it for an e-petition to be debated.
Commons Leader William Hague has notified Labour MP Natascha Engel, the committee's chairwoman, that the petition is now eligible to be considered for debate.
The killing happened in Helmand province in 2011 while Blackman was serving with Plymouth-based 42 Commando.
The victim was an Afghan who had been seriously injured in an attack by an Apache helicopter.
Blackman shot him in the chest at close range with a 9mm pistol before quoting a phrase from Shakespeare as the man convulsed and died in front of him.
Blackman told him: "There you are. Shuffle off this mortal coil, you c***. It's nothing you wouldn't do to us."
He then turned to comrades and said: "Obviously this doesn't go anywhere, fellas. I just broke the Geneva Convention."
During the trial Blackman was known as Marine A.
Blackman had denied murder, saying he believed the victim was already dead and he was taking out his anger on a corpse.
He was given a life sentence with a minimum of 10 years by a court martial in Bulford, Wiltshire, following his conviction in November 2013.
He was also "dismissed with disgrace" from the Royal Marines after serving with distinction for 15 years, including tours of Iraq, Afghanistan and Northern Ireland.
Blackman's conviction challenge was rejected by the Court Martial Appeal Court although his minimum term was cut to eight years because of the combat stress disorder he was suffering from at the time of the incident.
An e-petition on the Government's website addressed to the Ministry of Defence (MoD) asked: "Release Marine A & quash his murder conviction. Marine A has defended his country from a terrorist."
It received 107,169 signatures, meaning it passed the 100,000 signature threshold to ensure it is considered for a debate in Parliament.
After it received 100,000 signatures, Mr Hague wrote to Ms Engel: "As you are aware, this e-petition has now passed the threshold of 100,000 signatures, which makes it eligible for consideration for debate.
"I hope that the Backbench Business Committee will now consider the suitably of the issue for debate."
The MoD was prompted to reply when the e-petition received more than 10,000 signatures.
It said: "After a public trial in front of a court martial, at which he was legally represented, Marine A was found guilty of murder and two other Royal Marines were found not guilty of the offence.
"The identity of the victim does not change that verdict.
"It would be inappropriate for the Government to intervene in this independent judicial process."
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The Ministry of Defence cannot be prosecuted for any offence as it is a Crown body.