Cass Sunstein is a law professor, appointed regulatory "czar" in the Obama Administration. Though widely viewed as a liberal, Sunstein has taken many moderate positions in line with strict constructivism and supported the nomination of John G. Roberts to the Supreme Court. Sunstein's precise role in the administration is as yet undefined, and as a czar, he is answerable to no one except the president, acting as part of the "shadow government" identified by Glenn Beck. Sunstein has little background in regulation, and his appointment appears to have been motivated by his ties to Obama through the University of Chicago law school.
Sunstein has radical libertarian views on marriage. He has urged that the government should not be in the business of licensing marriages. He recommends civil partnerships, which could be between any two people, whether gay or straight. Sunstein also believes taxpayers should be forced to provide funding for abortion, even if they have religious or moral objections to it.
Sunstein is a favorite of liberals for his desire to ban hunting and his bizarre position that animals should be represented in court.
For a more detailed treatment, see Nudge (book).
Sunstein's resignation may have been due to the possibility he would hinder Obama's electability in November, as Sunstein could have been the focus of negative ads by Mitt Romney or the Super PACs that support Romney.