Haidar Ali Hussein, who was arrested in 2004, had challenged the lawfulness of interrogation and "tactical questioning" techniques used on captured prisoners.
But Lady Justice Hallett and Mr Justice Collins dismissed Mr Hussein's claim.
Mr Hussein had alleged that he had been physically ill-treated before and during questioning and subjected to "substantial periods of shouting".
A lawyer representing Mr Hussein had told judges one technique used by troops involved "screaming in a person's face from two to three inches away", and complained that the tactic could amount to criminal assault.
Ministry of Defence lawyers disputed the claim and said the technique was subject to constraints and safeguards.
The two judges had sat behind closed doors to watch footage of interrogations when hearing evidence in December.
Lady Justice Hallett said the technique, known as "challenge direct" was "strictly controlled". She added that "shouting at someone" was not assault.
Judges had been told that military chiefs made changes to techniques after Iraqi Baha Mousa died in Iraq nearly a decade ago.
An inquiry into Mr Mousa's death found that British soldiers had indulged in "an appalling episode of serious, gratuitous violence" on a number of Iraqi civilian detainees.