By What Sources do the Muslims Govern?

Muslims govern by laws laid down in the Qur'an and authentic Ahadeeth.

Evidence from the Noble Qur.aan
{And so judge (you O Muhammad) between them by what Allaah has revealed}, {Soorah al-Maa.idah, verse 49]

Evidence from the authentic Sunnah
((Allaah is the judge and to whom is the return)), [Transmitted by al-Bukhaaree and Muslim]