James Barry, of Nottingham, claimed he was provided with inadequate protective equipment and suffered “hearing loss and tinnitus” due to exposure to “excessive noise” during his service between 2013 and 2017.
The 34-year-old had ambitions to become a medic in the Royal Navy’s Special Boat Service, but became a lorry driver after being medically discharged.
In his High Court claim, Mr Barry argued he was exposed to “incredibly loud” gunfire while on training exercises and had to cope with yellow foam earplugs that often fell out during vigorous physical activity.
His lawyers argued there had been a “systemic, widespread and prolonged breach of duty” by the MoD.
The ministry apologised to Mr Barry in court and accepted it had been negligent by failing to provide the father-of-two with suitable hearing protection.
But the MoD claimed the ex-marine was partly to blame for his hearing loss because he failed to always use equipment provided, and should receive less compensation.
Mr Barry’s lawyers argued at a hearing in London in January that he should be awarded around £1.5 million in damages, while the ministry said he should only get about £250,000.
In a ruling on Friday, Mr Justice Johnson said the ministry had not shown Mr Barry was at fault over the use of “deficient” equipment and awarded him £713,716 in damages.
The judge said the available hearing protection was “inadequate and incompatible with other equipment”, adding: “lamentably, it appears that nothing was done by the MoD to address the obvious and serious problem.”
Mr Barry first noticed a problem with his hearing after returning from a training exercise dubbed “black alligator” in the United States between August and October 2014, the court was previously told.
Harry Steinberg KC, for Mr Barry, also said in written arguments that there were “exercises during basic training where hearing protection was not worn (and could not be worn) at all”.
The black alligator exercise likely resulted in “much or all” of the ex-marine’s hearing loss, the judge said in his ruling, with it involving “flash bangs, flash crashes, grenades, and a general purpose machine gun which was operated within 10 metres of Mr Barry”.
The training at a “dummy town” in California to practise urban warfare at one point saw an F16 fighter fly at low level above Mr Barry, while gunfire reverberated off metal shipping containers used as mock buildings.
After the exercise the ex-marine noticed “a constant, high pitched noise which was intrusive, particularly at night”, the judge said.
Mr Barry’s lawyers claimed he received insufficient hearing protection training, that use of equipment was not properly enforced and the ear defenders and earplugs provided were incompatible with a helmet and using a radio.
Andrew Ward, for the MoD, argued Mr Barry’s practice of not wearing ear protection in his left ear when using the radio went against instructions and amounted to “contributory negligence”.
But Mr Justice Johnson ruled that there was no evidence it was Mr Barry’s fault that earplugs often fell out, noting that he was “far from alone” in experiencing this.
The judge added that Mr Barry was involved in exercises that were “highly complex, challenging and potentially dangerous, involving intense simulated warfare and high cognitive demands”.
“It is understandable that replacement of hearing protection in the midst of a firefight, simulated, but with a high degree of realism, was not always at the forefront of Mr Barry’s mind,” the judge added.
The judge also said it was “not unreasonable” that Mr Barry removed an earplug “in the light of the defective equipment” when using a radio, with it not amounting to a failure to comply with instructions.
He concluded: “The MoD admits that Mr Barry has suffered injury and loss as a result of exposure to excessive levels of noise and that this was due to the MoD’s negligence and breach of statutory duty. It has not shown that Mr Barry was at fault.
“Mr Barry is entitled to compensation for his losses, without any reduction for contributory negligence.”