Ronald Dworkin, a legal philosopher and public intellectual of liberal views who insisted that morality is the touchstone of constitutional interpretation, died on Thursday in London. He was 81. The cause was leukemia, said Richard Revesz, the dean of the New York University School of Law, who announced the death. Dworkin had been a member of the school's faculty for many years and also taught at University College, London. Dworkin argued that the crucial phrases in the Constitution -- "the freedom of speech," "due process of law," "equal protection of the laws" -- were, as he put it, "drafted in exceedingly abstract moral language" that defied literal interpretation. His critics dismissed him as a "moral relativist."

James DePreist cut an imposing figure, even in the motorized wheelchair he rode to the podium, or seated on the low swivel chair from which he conducted. He usually got the best from the orchestras he led -- whether major ensembles like the New York Philharmonic and the Oregon Symphony, or student groups at the Juilliard School, where he was director of conducting and orchestral studies for seven years. Tall and heavyset, with a shaved head, a trim mustache and a beard that grayed in recent years, DePreist, who died Friday at 76, was one of the few black conductors to achieve international renown. He also published two books of poetry and received, among other awards, the National Medal of Arts from President George W. Bush in 2005.

Donald Byrd, one of the leading jazz trumpeters of the 1950s and early '60s, who became both successful and controversial in the 1970s by blending jazz, funk and rhythm and blues into a pop hybrid that defied categorization, died on Feb. 4 in Dover, Del. He was 80. Word of Byrd's death had circulated online for several days, but was not announced by his family. Almost from the day he arrived in New York City in 1955 from his native Detroit, Byrd was at the center of hard bop, a variation on bebop that put greater emphasis on jazz's blues and gospel roots. He performed with some of the most prominent jazz musicians of that era, including John Coltrane, Thelonious Monk, Sonny Rollins and Art Blakey.