adjective

treating all rivals or disputants equally.

the minister cannot be impartial in the way that a judge would be

unbiased,unprejudiced,neutral,non-partisan,non-discriminatory,anti-discrimination,disinterested,uninvolved,uncommitted,detached,dispassionate,objective,open-minded,equitable,even-handed,fair,fair-minded,just,without favouritism,free from discrimination,with no axe to grind,without fear or favour,on the fence