The word "arbiter" means a person or authority who has the power to make decisions or judgments in a dispute or conflict between two or more parties. Full definition
It often speaks of pluralism, but in fact insists upon its own singular role as arbiter of what counts as «inclusive» and «tolerant,» as well as «bigot» and «fundamentalist.» (firstthings.com)
Amazon is trying to set up itself as the ultimate arbiter of who is allowed to promote in the big (or at least bigger) leagues and who is not. (accrispin.blogspot.ru)
In particular, state channels — a generalization of the lightning network concept in Bitcoin — would permit conducting most transactions off - chain between parties directly, using the blockchain only as a kind of final arbiter in case of disputes. (bitcoinmagazine.com)