State Bank of India Act, 1955
18. Central Board to be guided by directions of Central Government
(1) In the discharge of its functions 4[including those relating to a subsidiary Bank], the State Bank shall be guided by such directions in matters of policy involving public interest as the Central Government may, in consultation with the Governor of the Reserve Bank and the Chairman of the State Bank, give to it.
(2) All directions given by the Central Government shall be given through the Reserve Bank and, if any question arises whether a direction relates to a matter of policy involving public interest, the decision of the Central Government thereon shall be final.