Is it permissible for a Muslim to be a policeman and a judge in a non -Muslim country?

Answer

It is haraam for a Muslim to be a policeman in a kaafir country and even in all these kufr-fisq Muslim states. A policeman has to act in accordance with the haraam/zulm laws of the country.

A Muslim judge who has to judge according to kaafir law, becomes a murtad. Allah Ta'ala says in the Qur'aan Majeed: "Whoever does not decree according to that Law revealed by Allah verily they are kaafiroon."

It is never permissible for a Muslim to become a judge to administer kuffaar law.