John Calvin Commentary Exodus 18:15

"And Moses said unto his father-in-law, Because the people come unto me to inquire of God:" — Exodus 18:15 (ASV)

And Moses said to his father-in-law. Moses replies sincerely, as if on a very praiseworthy matter, like one unconscious of any fault; for he declared himself to be the minister of God and the organ of His Spirit. Nor, indeed, could his faithfulness and integrity be called in question. He only erred in overwhelming himself with too much labor, and not considering his own private well-being, nor that of all the rest publicly.

Yet a useful lesson may be gathered from his words. He says that disputants come “to inquire of God,” and that he makes them know the statutes of God and His laws.

From this it follows that the purpose of political government is that God’s tribunal should be erected on earth, where He may exercise the judge’s office. This is so that judges and magistrates should not arrogate to themselves a power uncontrolled by any laws, nor allow themselves to decide anything arbitrarily or wantonly, nor, in a word, assume to themselves what belongs to God.

Then, and then only, will magistrates acquit themselves properly when they remember that they are the representatives (vicarios) of God.

An obligation is also imposed here upon all private individuals: they should not rashly appeal to the authority or assistance of judges, but should approach them with pure hearts, as if inquiring of God.

For whoever desires anything else except to learn from the mouth of the magistrate what is right and just, boldly and sacrilegiously violates the place which is dedicated to God.