The ruling could impact on the way future military inquests are held
The government's human rights watchdog has taken on the MoD in a test case which could extend human rights law to soldiers on battlefields abroad.
In April a High Court judge ruled that human rights laws can be applied to UK service personnel - even during combat.
He said sending soldiers to fight minus proper kit may breach human rights.
On Monday the Ministry of Defence challenged the ruling, while the Equality and Human Rights Commission has pledged to oppose the appeal.
Pushpinder Saini QC, representing Defence Secretary John Hutton, said Mr Justice Collins was wrong when he ruled in April last year that sending soldiers out on patrol or into battle without proper equipment could amount to a breach of their human rights.
The Equality and Human Rights Commission told the Court of Appeal that armed forces personnel serving overseas have a right to life under the European Convention and the Human Rights Act, whether or not they are physically on a military base.
BBC defence correspondent Caroline Wyatt said the court's decision could have far-reaching implications for the MoD and the UK's armed forces.
The ruling centres on a test case involving the death of a Territorial Army soldier, Pte Jason Smith, 32, from Hawick, in the Scottish Borders, who died of heatstroke in Iraq in 2003.
Pte Smith fell ill in temperatures of 60C (140F) while based at the Al Amara stadium, southern Iraq.
During his verdict at Pte Smith's inquest in November 2006, Oxfordshire's assistant deputy coroner, Andrew Walker, said the death was "caused by a serious failure to recognise and take appropriate steps to address the difficulty that he had in adjusting to the climate".
In April 2008 Mr Justice Collins said it had to be recognised that the lives of members of the armed forces when sent to fight or keep order abroad "cannot receive absolute protection".
But he ruled that soldiers did not lose all protection under the European Convention on Human Rights simply because they were in hostile territory carrying out dangerous operations.
He said that to send a soldier out on patrol or into battle with defective equipment could be a breach of the right to life enshrined within the convention.
Mr Saini said the government had conceded that Pte Smith was within the jurisdiction for human rights purposes because he died while in hospital at a UK base in Iraq.
He went on to say that Mr Justice Collins had made his ruling on an issue of general principle, that all members of the armed forces will stay within the rules of the European Convention when abroad.
"Accordingly, although the issue of jurisdiction is not material to the outcome of this case, the ruling is clearly of great general significance and cannot properly be allowed to stand."
Mr Saini argued that although the European Court of Human Rights did allow for a few exceptions to the general rule that human rights laws do not apply when abroad, they were of a "limited scope".
"So far as concerns analysis in the present case, the position of UK service personnel in active operations on the ground, on the streets in Iraq, does not fall within any of the exceptional categories."
He said that it does not follow that if members of the armed services come under the jurisdiction of the UK when military orders are given that they then fall within its authority for human rights purposes.
'Duty of care'
On Sunday Pte Smith's mother, Catherine, said: "I am very disappointed that the MoD has decided to appeal the court's decision. How can it be right to remove human rights from soldiers when they are at their most vulnerable?"
A spokesman for the commission said a ruling in their favour would mean the MoD will have to "provide greater protection to soldiers serving overseas" and that "bereaved families would be entitled to information about exactly what happened to their loved ones".
John Wadham, the commission's group legal director, said: "Our service personnel are required to lay down their lives for this country. In return, we should afford them the same human rights protection as every other citizen.
Scottish soldier Pte Jason Smith died of heatstroke in Iraq
"Of course, we recognise that the armed forces are operating in dangerous situations. This is not about an unreasonable expectation that the MoD will protect their life at all costs in a combat situation.
"It is about providing a good duty of care to them to ensure they remain as safe as possible."
An MoD spokesman said: "The MoD is appealing against Mr Justice Collins' ruling because it creates some uncertainty about the applicability of the European Convention of Human Rights.
"Justice Collins' ruling did not, in the MoD's opinion, reflect previous decisions on this issue... In particular, it did not reflect a previous judgment handed down in the House of Lords.
"This uncertainty could have a significant impact on the legal circumstances of deployed personnel, and how we conduct our operations once deployed," he added.