Personal bias may arise out of friendship, relationship, professional grievance or even enmity. Here again likelihood of bias is to be given more credence than for the actual bias. “it is difficult to prove the state of mind of a person. Therefore, we have to see whether there is reasonable ground for believing that he was likely to have been biased”. For example, in Tata Motor Challenge vs. Government of West Bengal, on the constitutional validity of Singur Land Rehabilitation and Development Act, Justice Saumitra Pal recused himself from the case, citing that he knew some of the people in relation with the case personally.
Official bias may arise in cases where an administrator who enunciates, and then has to carry out an official policy, is entrusted with the duty of hearing objections from the concerned persons as to the implementation of the policy. Here the general rule is that the bias that may be said to be likely to arise because the adjudicator has a general interest in the subject matter and administration of the policy in his official capacity, would not operate as a disqualification. The mere fact that the Registrar of Cooperative Societies has a power of general supervision over all Co-operative Societies, does not amount to inherent bias in him so as to disqualify him for the purpose of acting as an arbitrator or judge under Section 18 of the Rules made under the Co-operative Societies /Act 1912 to decide disputes between members of a Society (Viraj vs. State of Orissa 1967 SC 158). Thus, no official bias arises while senior officers adjudicate the Customs or Central Excise or Service Tax cases even though the investigations in the case might have been conducted by their subordinates.