In 2011, the United States district court in Phoenix, Arizona assigned Clarke as defense counsel to Jared Lee Loughner, the perpetrator of the January 8, 2011 Tucson, Arizona shooting. The Phoenix Public Defenders' Office had requested that Clarke be retained in order to allow Loughner to receive competent counsel without the possibility of a community-wide conflict of interest arising from proceedings against him for his alleged role in the shooting. In 2012, Clarke brokered a deal sparing Loughner's life in exchange for a guilty plea to 19 counts, including the wounding of then congresswoman Gabby Giffords. Loughner is serving life in prison without parole.