Gideon v. Wainwright (1963)
Clarence Earl Gideon was charged with breaking into a Florida pool hall and stealing money from a vending machine.  He was too poor to hire a lawyer, and defended himself after the Florida court said it only had to provide attorneys to indigent defendants in capital cases.  The US Supreme Court unanimously ruled otherwise, overturning its 1942 decision in Betts v. Brady.   In Justice Black's words, in the American system of justice "lawyers in criminal cases are necessities, not luxuries."  The court therefore held that indigent defendants in state courts had the Sixth Amendment right to be represented by a court-appointed attorney if they could not afford to hire their own.

http://www.oyez.org/cases/1960-1969/1962/1962_155/