Simplify the following text for a Grade 5 native English-speaking person.
Original: David Hackett Souter ( ; born September 17 , 1939 ) served as an Associate Justice of the Supreme Court of the United States from 1990 until his retirement on June 29 , 2009 .
Simplified: He was born September 17 , 1939 . Souter has been an Associate Justice since 1990 .