As first discussed here in July 2007, Harold Koh - recently appointed the top legal adviser at the State Department - supports illegal immigration. The fact that he supports illegal activity is cut and dried; his actual position on U.S. sovereignty is less clear but it doesn't look very good. From this:

He's a fan of "transnational legal process," arguing that the distinctions between US and international law should vanish.

What would this look like in a practical sense? Well, California voters have overruled their courts, which had imposed same-sex marriage on the state. Koh would like to see such matters go up the chain through federal courts -- which, in turn, should look to the rest of the world. If Canada, the European Human Rights Commission and the United Nations all say gay marriage should be legal -- well, then, it should be legal in California too, regardless of what the state's voters and elected representatives might say.

He even believes judges should use this "logic" to strike down the death penalty, which is clearly permitted in the US Constitution.

The primacy of international legal "norms" applies even to treaties we reject. For example, Koh believes that the UN Convention on the Rights of the Child -- a problematic document that we haven't ratified -- should dictate the age at which individual US states can execute criminals. Got that? On issues ranging from affirmative action to the interrogation of terrorists, what the rest of the world says, goes.

Even Ed Morrissey thinks she might be overselling parts of this (specifically the part relating to sharia law: link), but she's probably close to his actual views. What would be helpful would be a review of his statements and actions by a legal scholar.

UPDATE: There's a similar editorial from Investors Business Daily here.

UPDATE 2: A much stronger argument against him on these issues is made here. It includes a quote from a law review article he wrote in which he referred to himself as a "transnationalist", which he then defined:

...The transnationalists believe in and promote the blending of international and domestic law; while nationalists continue to maintain a rigid separation of domestic from foreign law. The transnationalists view domestic courts as having a critical role to play in domesticating international law into U.S. law, while nationalists argue instead that only the political branches can internalize international law... The transnationalists believe that U.S. courts can and should use their interpretive powers to promote the development of a global legal system, while the nationalists tend to claim that U.S. courts should limit their attention to the development of a national system.