Disinterested means "unbiased by personal interest" (Oxford English Dictionary). It is sometimes used wrongly for uninterested (i.e. not interested). A Minister recently said in the course of a speech in Parliament:
I hope that [what I have said] will excuse me from the charge of being disinterested in this matter.
A public man dealing with public business can never be "charged" with being disinterested, as if it were a crime. It is his elementary duty always to be so.