arbiter
arbiter
/ˈɑːbɪtə(r)/
noun
(formal) arbiter (of something) a person with the power or influence to make judgements and decide what will be done or accepted
The law is the final arbiter of what is considered obscene.
an arbiter of taste/style/fashion
This style would be dismissed as too ornate by contemporary arbiters of taste.
e.g.