arbiter

A person appointed, or chosen, by parties to determine a controversy between them; an arbitrator.

In order to protect individual liberty there must be an arbiter between the governing powers and the governed.

A person or object having the power of judging, determining, or ordaining; one whose power of deciding and governing is not limited.

Television and film, not Vogue and similar magazines, are the arbiters of fashion.

The grapholect of Standard English is not the exclusive system that arbiters of cultural purity wish to 'correct' us into believing

A component in circuitry that allocates scarce resources.

To act as an arbiter.

Worse, since there was no institution to arbiter disagreements between Parliament and the government, whenever Parliament voted against the government on the smallest issues, coalitions fragmented, and governments had to be recomposed.