St. Louis Circuit Attorney Jennifer Joyce says that during her 15 years as a prosecutor, she’s worked with scores of St. Louis police officers. The “vast, vast majority” are “outstanding,” she said, and citizens can have the “utmost confidence” in their integrity.

“But we tend to emphasize the rare exception and not the rule,” she added. “That’s human nature.”

Robert Patrick of the Post-Dispatch reported Wednesday that police brass say in court filings that they believe “one or more” officers “have included false information in affidavits” for warrants.

In April the Post-Dispatch reported that Ms. Joyce’s office had quietly dropped cases associated with two officers who had been accused by defense lawyers of lying on search warrant applications.

Now comes a group filing suit as “John Doe Police Officers” claiming that they may use “confidential sources” in police investigations as they please — with accountability to no one.

The unidentified officers, along with the police union, have filed suit against the St. Louis Police Department and the Board of Police Commissioners. They complain that they are being hauled before the department’s Internal Affairs Division and compelled to disclose the identity of “anonymous sources.”

In their lawsuit, the “John Doe Police Officers” say if officers are forced to disclose the identities of their informants, a terrible tangle of problems would ensue:

• Informants generally would be less willing to come forward if they believe their cover might be blown — even to superior officers in the department.

• Informants whose identities are revealed to Internal Affairs could be exposed to retribution if internal affairs investigators follow up and start asking questions in the community.

• If that happens, the informants would lie about being informants. That would expose the officers themselves to disciplinary action.

The officers have asked the St. Louis Circuit Court to permanently enjoin the department “from asking or compelling . . . any John Doe police officer to disclose the identity of any anonymous source utilized by said officer.”

Informants play a valuable role in law enforcement, but their willingness to provide information often depends on their identities being protected. They could be exposed to serious danger if their identities are carelessly revealed.

Police officers must exercise the utmost caution when dealing with informants — who might have deep motivations to lie about many things.

But the integrity of the system cannot be protected by insulating it from higher review, leaving all responsibility to individual officers. The contrary is true.

Careful supervision is the only way to protect reliable informants, honest officers and the public at large.

Special orders govern the use confidential informants; the orders contain caveats, conditions and checks and balances that call for involvement of supervisors and that limit individual officer’s authority to promise anonymity.

Circuit Judge Robert Dierker granted the officers temporary relief, pending a hearing later this month. But the ruling must not stand. When there are reasons to doubt the informants’ reliability — or even their existence — officers must be subject to questions.

What’s more, Missouri law grants no protection to officers who make fraudulent or bad faith claims of confidentiality.

Ms. Joyce correctly observes “our goal as prosecutors is to make sure juries receive good, credible, trustworthy evidence,” and that “the right people are being held accountable for crimes.”

Meeting those goals depends on the police department’s careful oversight of confidential informants.