In Shepperd v. United States, an attorney represented his client, the criminal defendant, and also the government's key witness at the same time. Two weeks before trial, this conflict of interest was finally made known to the defendant, who immediately obtained new counsel. The new counsel informed the trial court about the conflict and requested a continuance of the trial. The trial court, however, held that the trial must proceed as planned. The defendant got 30 years from the trial. 

The case got appealed to the Fifth Circuit. Justice Willett, writing for the Court, was rather assumed by this clear conflict of interest. He actually wrote "Oops." as his reaction in this opinion. Nevertheless, the Court refused to vacate the verdict, but remanded the case back to the trial court for an evidentiary hearing. 

Host: Prof. Leo Yu, SMU School of Law 
Guest: Prof. Pamela Metzger, SMU School of Law, Director of the Deason Criminal Justice Reform Center