Colonel Tim Collins and Colonel Jorge Mendonca face MPs on the Defence Committee.
MPs have been hearing from two former Commanding Officers on how they feel veterans could be better protected from investigations into historical events.
Members on the Defence Committee are looking into whether there should be a time limit for the investigation of incidents on the battlefield.
Colonel Tim Collins and Colonel Jorge Mendonca, both of whom served in Iraq, answered questions.
The evidence session is the first of the Committee’s inquiry into the issues surrounding legacy investigations into Operations in Iraq, Afghanistan and Northern Ireland.
Colonel Mendonca said previous cases have made things very difficult for those currently serving and could slow down the effectiveness of the Army.
"An Army that works really well and doesn't question, doesn't seek things in writing, doesn't look over their shoulder"
Colonel Mendonca went on to tell the committee, soldiers could question their actions and fear consequences.
"And doesn't act, knowing that 10, 20, 30 years later their families lives are going to be decimated by an investigation"
Colonel Collins said soldiers would now need to record everything to safeguard against future prosecution.
The session follows comments made by the Defence Secretary Gavin Williamson in July in which he said he was "prepared to go to any lengths" to prevent what he described as a "vendetta against former service personnel" who served in Northern Ireland.
Mr Williamson later announced he had set up a team to look at proposals to protect armed forces veterans from prosecution for historic allegations.
As well as working to establish how witnesses feel veterans could be better protected from investigations into past events, it will explore what support is provided by the Ministry of Defence.