LOS ANGELES – A ruse set up through bogus subpoena documents to snag a former Orange County, Calif. sheriff for criminal wrongdoing was a “legitimate investigative technique” according to the government’s brief filed before a federal appeals court.

In response to an appeal filed by former sheriff Mike Carona, the Dec. 18 brief asserts that federal prosecutors did not violate California’s Rules of Professional Conduct when they used a cooperating witness to contact Carona using two fake subpoena documents.

Carona was convicted in January on one count of witness tampering but acquitted on five other counts, including conspiracy to commit honest services fraud. Prosecutors had alleged that he used his office to enrich himself, his friends and his family. He was sentenced to 5 ½ years in prison and ordered to pay a $125,000 fine.

In his Oct. 13 appeal before the U.S. Court of Appeals for the 9th Circuit, Carona claimed that the conviction should be overturned because U.S. District Court Judge Andrew Guilford, of the Central District of California, should have allowed the jury to consider evidence of prosecutorial misconduct tied to the witness tampering count. The witness tampering count claimed that Carona influenced the grand jury testimony of a local businessman, Don Haidl, who served as assistant sheriff under Carona.

Prosecutors introduced evidence of recorded audiotapes of a meeting between Carona and Haidl in August 2007. Haidl, who pleaded guilty to one count of filing a false tax return, arrived at that meeting as a government witness wearing a wire and holding the fake subpoena documents, intended to make Carona believe that Haidl had been asked to testify before a grand jury. Carona, in his appellate brief, claimed that prosecutors should not have attempted the ruse because Carona had retained counsel at the time — a clear violation of California Rule of Professional Conduct 2-100. That rule states that a member of the bar “shall not communicate directly or indirectly about the subject of the representations with a party the member knows to be represented by another lawyer in the matter unless the member has the consent of the other lawyer.”

The brief filed by federal prosecutors asserts that the “use of the bogus subpoena attachments was a proper ruse that merely offered Carona the opportunity to misuse the powers of his office and engage in criminal activity, an opportunity which, as the recordings confirm, defendant readily embraced.” The government noted that the professional conduct rule does not prohibit communications “otherwise authorized by law.”

Guilford, who sits in Santa Ana, Calif., found that the government had violated Rule 2-100 because “Haidl improperly became the ‘alter ego’ of the prosecutors.” But the judge refused to suppress the recorded tapes, stating that no constitutional rights were compromised. He denied several other requests — an instruction permitting the jury to consider the violation, introducing evidence about the violation, and disqualifying the prosecutors — on ground that the State Bar of California’s disciplinary procedures were appropriate remedies.

Carona’s attorneys have referred prosecutors, including Assistant U.S. Attorney Brett Sagel, to the State Bar of California, but no disciplinary action was taken, according to Carona’s brief.

Prosecutors, in their brief, said the judge’s rulings were correct.

But they also asserted that no violation occurred.

“It is well established in this circuit that pre-indictment, non-custodial, covert contacts in criminal investigations, including undercover operations and meetings, are generally permissible, even if directed at individuals known to be represented by an attorney in connection with the subject matter under investigation,” the brief states.

Carona’s lawyer, John Cline, a partner in the San Francisco office of Jones Day, did not return a call for comment.

Amanda Bronstad can be contacted at abronstad@alm.com.