American philosopher and constitutional law expert Ronald Dworkin, a liberal scholar who argued that the law should be founded on moral integrity, has died at the age of 81. His family said Dworkin died of leukemia in London early Feb. 14.

Dworkin was a professor of law at New York University and emeritus professor at University College London. He was one of the best known and most quoted legal scholars in the United States and also an expert on British law.