From Wikipedia, the free encyclopedia. Stephen Gaghan (born May 6, 1965) is an American screenwriter and director. He is noted for writing the screenplay for Steven Soderbergh's film Traffic, based on a Channel 4 series, for which he won the Academy Award, as well as Syriana which he wrote and directed. Description above from the Wikipedia article Stephen Gaghan, licensed under CC-BY-SA,full list of contributors on Wikipedia.