The Qur'aan states that those who do not judge according to the Law of Allah, they are kaafiroon.

Answer

Those who do not judge by the Law of Allah, the Qur'aan says that they are the Kaafiroon. There are two kinds of 'kaafiroon' in this context. The one kind will be those who outrightly reject Allah's Law. They do not believe in it. They are the kaafiroon of the highest degree such as the modernist political leaders who are in power in most of the Muslim countries. They are men such as Hosni Mubaarak (Egypt), Musharraf (Pakistan), Zainul Abideen (Tunisia), Assad (Syria), etc.

Then there are the other kind of 'kaafiroon' who are outwardly kaafir because they judge by kufr law whilst they believe in Islam and its laws. They are like such fornicators who commit zina while believing zina is haraam. In this class of 'kaafiroon' are rulers such as the Saudi Arabian rulers.

However, in terms of the fatwa of the Shariah both groups will be branded Kaafiroon. Allah Ta'ala will judge them in the Hereafter.