Law clerk, Justice Hugo L. Black, Supreme Court of the United States Court, Washington, 1959-1960;visiting professor School Law, University Texas, summer 1960;visiting professor School Law, Yale University, fall 1990;associate, Jones, Day, Cockley & Reavis, Cleveland, 1960-1964;professor of law, University of California, Berkeley, 1964-1991;Roger J. Traynor professor of law, University of California, Berkeley, since 1991. Of counsel Baker and McKenzie, San Francisco, 1974-1975. Academic visitor London School Economics, 1985, Cambridge U., 1994, U. Edinburgh, 1994.
Visiting fellow Wolfson College, Cambridge, 1994, U. Innsbruck, 1996, Trinity College, Dublin, 1997. Visiting professor Yale University, University Texas, U. Leiden, U. Tilburg, U. Tokyo, U. San Diego, others. Lecturer universities Cologne, Hamburg, Kansei, Kyoto, London, Munich, Seoul, Tokyo, Tilburg, Amsterdam, Rotterdam, Vienna, Tohoku, Tübingen, others.
Member of advisory board Tax Management.