impartial

英[ɪm'pɑːʃ(ə)l] 美[ɪm'pɑrʃəl]

1. showing lack of favoritism;

"the cold neutrality of an impartial judge"

2. free from undue bias or preconceived opinions;

"an unprejudiced appraisal of the pros and cons"

"the impartial eye of a scientist"