 His essay about Sonia Sotomayor, then a potential Supreme Court nominee, provoked controversy for its use of anonymous sources, however, other media outlets, including the "New York Times", had relied upon similar sources.Rosen worked with Justice Elena Kagan for many years and is the brother-in-law of Justice Department attorney Neal Katyal.In an opinion piece published after Kagan's nomination hearings and before the Senate's vote on her confirmation, Rosen encouraged Kagan to look to the late Justice Louis Brandeis as a model "to develop a positive vision of progressive jurisprudence in an age of economic crisis, financial power and technological change."