Shaykh Abdul-Azeez Ar-Raajihee was asked (audio here):

This person asks about the Sharee'ah ruling concerning the ruler who rules by the French Secular Laws alongside the knowledge that he claims Islaam, prayers, fasts and makes hajj. So what is to be said about him?

The Answer:

When he believes in [their] permissiblity (i'taqada al-jawaaz), when he believes that judgement by the French [secular] laws is permissible, then he is a kaafir. When he believes that it is permissible for him [to do that].

As for when he does not believe this, or he has a doubt (shubhah), then it is necessary for the proof to be established against him.

And some of the people of knowledge have held that when he alters the religion (ghayyara ad-deen) in all of the affairs of the state, then he is a kaafir, because he has changed (baddala) the religion, and al-Haafidh Ibn Katheer (rahimahullaah) has gone to this [view] in his tafseer, and also Shaykh Muhammad bin Ibraaheem (rahimahullaah) in his treatise "Tahkeem ul-Qawaaneen". So when he changes the religion, the whole of it, from head to heel (i.e. top to bottom), in all of the affairs of the state, in everything - not in part of it - then he is a kaafir, because he has altered the religion.

And then some others have said that it is necessary for the proof to be established against him, for he could be ignorant, or have some doubt (shubhah). Our respected Shaykh, Abdul-Azeez Bin Baaz (may Allaah's mercy upon him), chose this view.

This article was published previously nearly eight years ago in 2002, and the audio file can be downloaded here (in real audio format).

Refer also to this article:

• Shaykh Ibn Jibreen on What is Manifest Clear Kufr and Ruling With the Secular Laws - (see here)