The Ministry of Defence operated "flagrantly" outside the laws on detention, a spokesman from lawyers Leigh Day said.
The law firm, who represent Afghan farmer Serdar Mohammed in his damages claim for assault, false imprisonment and human rights breaches against the Government, made the comment after the High Court ruled UK forces' detention policy in Afghanistan was unlawful.
When we send our troops abroad it is the Ministry of Defence's job to ensure that the mechanisms are put in place to ensure that they operate within the rule of law.
As the court has made clear, the MoD fully understood the parameters of the law regarding detention and yet they decided to operate flagrantly outside those rules.
More top news
Two men have been arrested after a methamphetamine lab was discovered inside a Taco Bell restaurant in the US.
The Labour leadership contender has vowed to renationalise Britain's railway network "line-by-line" if he becomes prime minister.
Two passenger trains have derailed while crossing a bridge in India, leaving at least 20 people dead and injuring hundreds more.