Sajid Javid reportedly refused to halt weapons exports to Saudi Arabia last year despite being warned by a senior civil servant that sales should be suspended over human rights concerns.
The first day of a judicial review into UK arms sales to Saudi Arabia heard that the then Business Secretary was told a year ago about concerns that weapons could be used to kill civilians in Yemen.
Edward Bell, head of the Export Controls organisation, wrote in an email about the decision: "To be honest, and I was very direct and honest with the Secretary of State, my gut tells me we should suspend [weapons exports to the country]."
Half of the three day hearing now underway at the High Court will be held in secret so the Government can produce sensitive evidence.
The case brought by Campaign Against Arms Trade (CAAT) argues that exports should not go ahead if there is a "clear risk" the equipment could be used to break international humanitarian law.
The case continues.