The parents of Columbine gunman Eric Harris had asked a judge to bar attorney Geoffrey Fieger from representing Isaiah Shoels' family, saying he tried to prejudice future jurors through accusations of racism.
Witnesses have said Shoels, 18, was gunned down because he was black and an athlete.
Shoels' family sued the parents of Harris and Dylan Klebold, saying they negligently allowed their sons to amass the weapons used in the April 1999 rampage. Harris and Klebold killed 13 people before killing themselves.
Judge R. Brooke Jackson on Wednesday ruled that Fieger's conduct, which included holding a news conference and contacting the media, could not have unduly prejudiced future jurors because the case has already been highly publicized.
Fieger is licensed to practice in Michigan and needed Jackson's permission to represent Shoels' family in Colorado.