The attorney general has revealed how he was taken on to a Navy submarine to make clear the need for him to give speedy legal advice in times of war.
Lord Goldsmith was taken in a submarine early in his job
Lord Goldsmith told peers he had to be on call constantly during conflicts to advise on legality of military action.
He said that soon after taking up his job he went into a submarine to see first-hand where decisions were made.
Once a periscope was raised there was only a 20-minute window to get advice before launching an attack, he said.
Lord Goldsmith, the government's top lawyer, gave the insight into his war role when giving evidence to the Lords constitution committee, which is investigating war making powers.
He said there were general rules of engagement for troops in conflicts but international humanitarian law also meant legal advice was needed on attacking specific targets.
During the Afghanistan conflict, he had seen papers on attacks on an almost daily basis.
When he was not consulted, it was because other lawyers were advising military commanders in the field, he said.