Law & Order: Special Victims Unit Guest cast, played by Viola Davis Episode 4x14: Mercy (Jan 31, 2003) Episode 4x23: Grief (May 2, 2003) Episode 6x01: Birthright (Sep 21, 2004) Episode 6x08: Doubt (Nov 23, 2004) Episode 8x08: Cage (Nov 21, 2006) Episode 9x19: Cold (May 13, 2008) Episode 10x05: Retro (Oct 28, 2008)