CHAPEL HILL - Whether the defendants in the Duke lacrosse case are guilty or innocent, Durham District Attorney Mike Nifong should disqualify himself, or be disqualified, from the case.

On Friday, Nifong's own witness essentially accused him of breaking the law. An actual conflict of interest now exists between Nifong's need to defend himself against possible charges of misconduct and his obligation to prosecute the case fairly and effectively.

In court Friday, the head of a lab that Nifong retained to analyze DNA samples testified that he and Nifong intentionally decided to exclude from the expert's report the fact that DNA analyzed from the clothes and body of the accuser did not belong to any of the defendants but came instead from unidentified males.

N.C. General Statute 15A-903 requires that a prosecution expert provide a report of the results of any tests performed and that the prosecutor furnish that report to the defense. Deciding to exclude these results is deciding to violate this law.

A prosecutor also has an obligation under the U.S. Constitution and under N.C. Rule of Professional Conduct 3.8 to disclose to the defense evidence which tends to suggest the innocence of a defendant -- including evidence that calls the credibility of a state witness into question. DNA results showing the absence of DNA material from the accused and the presence of DNA material from other men goes to the credibility of the accuser's account and therefore needs to be disclosed.

In addition to these disclosure requirements, a prosecutor has an ethical obligation not to ignore evidence which suggests the innocence of the accused. A comment to Rule 3.8 provides that "a prosecutor should not intentionally avoid pursuit of evidence merely because he or she believes it will damage the prosecutor's case or aid the accused." It is not clear that Nifong has ever followed up on the DNA evidence described.

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North Carolina law provides for the disqualification of a prosecutor from a case only in the event of an actual -- not just potential -- conflict of interest. An actual conflict of interest appears to exist in this case because Nifong must either challenge the credibility of his own DNA expert's testimony or he must admit to intentional misconduct.

Nifong also has a vested interest in finding that the presence of DNA evidence of unidentified men on the body and clothes of the accuser does not call the credibility of the accuser's account into question, in order to minimize the significance of the evidence he did not disclose. This interest conflicts with Nifong's duty as a prosecutor to impartially evaluate this potentially exculpatory evidence. Prosecutors are ethically obliged to seek justice, not merely to convict.

Nifong has said that privacy concerns influenced his decision. Privacy interests do not justify violations of either the discovery statute or a prosecutor's constitutional and ethical obligations.

Nifong has also argued that the test results in question were disclosed when the defense specifically asked for them. Prosecutors do not get to play "Battleship" with their discovery obligations by requiring defense lawyers to score a direct hit with a discovery request. Prosecutors must affirmatively disclose what the law requires.

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Nifong may not yet have fully told his side of the story. His account may differ from that of his DNA expert in ways that absolve him of intentional misconduct. His need to seek such absolution is the heart of the conflict, however. Disqualifying Nifong would free him to fully defend himself against charges of misconduct without compromising the fair prosecution of the case.

A finding of willful misconduct would carry particularly serious consequences for Nifong because he is not just a prosecutor but a district attorney. N.C. General Statute 7A-66 provides for the removal from office of a district attorney who has engaged in willful misconduct.

Disqualifying a prosecutor from a case is an extreme measure, although not as extreme as removing him from office or prosecuting him criminally, as U.S. Rep. Walter Jones has suggested.

Disqualifying Nifong from the case should not be interpreted as a victory for the defense or as a defeat for the accuser. The defense in fact might prefer that Nifong continue to handle the case on the theory that his credibility with the court and with the public has been compromised. If the defendants are guilty, a prosecutor who is not hamstrung by allegations of misconduct would be in a better position to secure convictions.

A prosecutor with a conflict of interest cannot produce a result in which the community can have confidence. Whether the defendants were eventually convicted or acquitted, Nifong's own ethical and legal troubles would taint the result.

The accuser, the defendants and the community are all entitled to an untainted result. A prosecutor's ultimate obligation is to the truth, and only prosecutors free of conflicts of interest should be entrusted with that obligation.