Constitution of India, Arts.226, 16 – evidence Act (1872), S.115 – Promotion of Class-IV employees to Class-III – Whether principle of estoppel and acquiescence will prevail over statutory service rules prescribing the procedure for promotion of ClassIV employees to ClassIII working in the Banaras Hindu University BHU, Varanasi, a Central University? Principle is that principle of estoppel cannot override the law. The manual duly approved by the Executive Council will prevail over any such principle of estoppel or acquiescence – The members of the Selection Board or for that matter, any other Selection Committee, do not have the jurisdiction to lay down the criteria for selection unless they are authorised specifically in that regard by the rules made under Article 309. It is basically the function of the Rule making authority to provide the basis for selection.