God's law is the leader's unfailing guide

Deuteronomy 17:14-20
The king of Israel to be:
1)Condition: Be sure to appoint over your the king the Lord your God chooses.
                     be from among your own brothers. Do not place a foreigner.
2)Principle: Do not acquire great number of horses.    military force.
                   Do not make the people return to Egypt.  slave of world.
                   Do not take may wives, or his heart will be led astray.    family & life.
                   Do not accumulate large amounts of silver and gold.      bribe
                   Do not consider himself better than his brothers and turn from the law and the decrees.
                              humble himself could be wise.
3)The Law: He is to write for himself on a scroll a copy of this law, taken from that of a priests, who are Levites.    Won't forget the mercy of the Lord and learn to reverse the Lord.
Why?
The Lord knows what the Israel will have a king over them like all the nations around them. They won't like the Lord be their king.
The Lord allow it happen, but gave them the principle to follow, then they and their descendants will reign a long time over his kingdom in Israel.
God permits the monarchy, but does not set it up. The dangers foreseen here- military aggression and sensuality leading to idolatry- became an uncomfortable reality later in Israel's history.
God's law is the king's unfailing guide.
How?
When I attend a new president election I should follow this instruction to vote my decision to the one who God likes.
For me to be a leader I should check myself has followed these a few principles.