There is nothing "nuanced" about Imam Feisal Rauf's belief in the primacy of Sharia (Islamic Law) in society -- any society.

...the American political structure is Shariah compliant, for a state inhabited predominantly by Muslims neither defines nor makes it synonymous with an Islamic state.

...(it) also would not be a violation of church-state separation to have a subsidiary entity within judiciary that employs religious jurists...to comment on the compliance of certain decisions...to provide guidance on how Shariah compliant these decisions are...

It can become truly Islamic only by virtues of a conscious application of the sociopolitical tenets of Islam to the life of the national, and by an incorporation of those tenets in the basic constitution of the country.

 ...God's role in the explicit philosophical construct of the law makes a big difference between the modus operandi of a righteous Muslim judge in a Muslim court and a righteous Western judge in a Western court. The judge who sits in judgment in an Islamic court sits in lieu of God as His worldly representative [khalifa] and is held responsible by God to His values. The Muslim judge explicitly ‘reports to God.' The judge who sits in a Western court is only explicitly responsible to the Constitution, the interpretations of a civil law and its rules

...And since a Shariah is understood as a law with God at its center, it is not possible in principle to limit the Shariah to some aspects of human life and leave out others."

..The Shariah thus covers every field of law-public and private, national and international-together with enormous amounts of material that Westerners would not regard as law at all, because the basis of the Sharl'ah is the worship of, and obedience to, God through good works and moral behavior. Following the Sacred Law thus defines the Muslim's belief in God.