The use of criminals as informants to testify against other suspects in exchange for leniency is fraught with peril. On one hand, informants might be untruthful in order to give the prosecution what it wants in their testimony and thereby ensure leniency in their own cases. "Their testimony is essentially bought and paid for," said John Wesley Hall Jr., president of the National Association of Criminal Defense Lawyers.

On the other hand, prosecutors believe that deals to obtain testimony from informants are necessary evils, and often the only practical way to obtain information about secretive organized crime figures. "Often the people who are in the best position to be witnesses in a case are the people who themselves have been involved in the criminal activity," said Maryland U.S. Attorney Rod J. Rosenstein.

The evidence shows that the testimony of criminal informants has resulted in the convictions of many serious criminals. However, the evidence also shows that the inability to independently confirm the testimony of most informants has resulted in wrongful convictions. In addition, trading the liberty of one criminal (the informant) for another (the defendant) may not always be in the public's long-term interest in safety, because leniency is based on cooperation rather than culpability.

• Evaluate the moral permissibility of the prosecutor's decision to use convicted criminals, whose sentences are not yet final, to testify against another suspect.