"It was not proper for me to appear," was his answer to the bench of justices T S Thakur, A R Dave and A K Sikri.
Sibal said he was a minister in the previous UPA government and had taken a particular view.
"I have gone through several files. It is not proper for me to appear," he told the bench which after pronouncing the judgement in Sahara case wanted to know the reason for not appearing in the NJAC matter.