American philosopher and legal scholar Ronald Dworkin dies in London at 81

The American philosopher and constitutional law expert Ronald Dworkin has died at the age of 81.

Dworkin's family says he died early Thursday in London of leukemia.

Dworkin was a professor of law at New York University and emeritus professor at University College London.

He was best known for articulating the principle that the most important virtue the law can display is integrity — understood as the moral idea that the state should act on principle so each member of the community is treated as an equal.

A frequent contributor to the New York Review of Books, Dworkin's books included "A Matter of Principle," ''Law's Empire," and "Justice for Hedgehogs."

He is survived by his wife Irene Brendel Dworkin, his children Anthony and Jennifer Dworkin and two grandchildren.