"... Our mandate is very clearly to ensure that policy once formulated must be most optimally implemented," Rai said at a book release function here.
Irrespective of whatever debate taking place in the country, he said "policy formulation is indeed the sole prerogative of the government. We do not at any point of time ever feel that we should either be part of policy formulation, process or question the policies."
In checking efficacy of the efficiency of government schemes and project, he said "there is a very thin dividing line, where we do at times assess the optimality or sub-optimality of a particular policy in the course of its devolution."
However, he added, the role of CAG has changed and it has to see that whatever policy is approved by Parliament or the government meets the objective.
During an interaction with editors last year in June, Prime Minister Manmohan Singh had made critical remark about CAG pointing out "never in the past has the CAG decided to comment on a policy issue. It should limit the office to the role defined in the Constitution."
"We do certify the account, check the accounts and scrutinise but there is a clear mandate given to us. And that mandate we must fulfill. In fulfilling that mandate, we also have to ensure that we do not cross the rule," he said.