Former Orange County Sheriff Mike Carona has asked an appeals court to reverse his 2009 conviction for witness tampering.

A panel of the 9th U.S. Circuit Court of Appeals heard arguments Wednesday in Pasadena.

The former sheriff was sentenced to 5 1/2 years in prison for trying to persuade ex-assistant sheriff Don Haidl to lie during a grand jury probe.

Carona's lawyers argued that prosecutors broke an ethical rule when they arranged for Haidl to secretly record an August 2007 conversation despite knowing Carona had retained a criminal defense attorney.

A federal attorney argued that the government used what he called "permissible decoys."

Carona was acquitted in January of conspiracy, mail fraud and a second witness tampering count in a sweeping public corruption case.