U.P. v. Gobardhan Lal (2004) 11 SCC 402

allegations of mala-fides must inspire confidence of the Court and ought not to be entertained on the mere asking of it or on consideration borne out of conjectures or surmises and except for strong and convincing reasons, no interference would ordinarily be made with an order of transfer. That the burden of proving mala-fides is on a person leveling such allegations and the burden is heavy, admits of no legal ambiguity. Mere assertion or bald statement is not enough to discharge the heavy burden that the law imposes upon the person leveling allegations of mala-fides; it must be supported by requisite materials.