St. Louis Circuit Attorney Kim Gardner delivered an “exclusion list” to the city police department on Tuesday. On that list were the names of 28 police officers — and Gardner says that she will no longer consider cases brought to her office by any of those on the list.

Gardner’s office gave no reason for submitting the list, but did note that previous cases brought by those same officers were under review for “viability.”

Warrant applications from the affected officers may also be denied according to an email obtained by the St. Louis Post Dispatch in which Maj. Michael Sack, of the Bureau of Professional Standards, referenced Gardner’s Chief Warrant Officer Chris Hinckley as the point of contact for any concerns.

In his email, Sack quoted Hinckley’s email. “Mr. Hinckley advised, ‘warrant applications involving officers (sic) as essential witnesses will be refused if their participation is essential to the successful prosecution of the case. Cases previously issued where the above officers are essential witnesses will be reviewed for viability.'”

While Gardner’s office has given no official reason for the case review or the exclusion list, many of her critics fear that the move could be political. Gardner’s relationship with local police departments has long been contentious — and a couple of recent high profile cases have not done much to mend fences.

In 2017, protests broke out after Gardner failed to get a conviction against former police officer Jason Stockley for the shooting death of Anthony Lamar Smith. Stockley has since filed a lawsuit against former circuit attorney Jennifer Joyce — who filed charges on her way out the door and left the prosecution in Gardner’s hands — for defamation and malicious prosecution.

Gardner was also the subject of a formal complaint, filed earlier this week, alleging that she suborned perjury and withheld evidence in the case she brought against former Missouri Gov. Eric Greitens.

A formal complaint has been filed with the Missouri Bar Association against St. Louis Circuit Attorney Kim Gardner for her handling of the Greitens case. https://t.co/o1B080bcg2 — KMOX St. Louis News (@kmoxnews) August 27, 2018

Despite sketchy appearances, according to St. Louis University law professor Anders Walker, what Gardner is doing isn’t exactly illegal. However, he did offer a caveat. “She may jeopardize her relationship with the police department, he explained, “And it could be a problem politically if the voters of St. Louis don’t agree. It could be a positive, if she has singled out officers she thinks cannot be trusted and is proven correct.”

The 28 officers on the list account for 2.5 percent of the police force and 5 percent of front-line officers, and according to an internal email obtained by the St. Louis Post Dispatch, all of the affected officers are to abide by their mission statement and continue doing their jobs to protect the people of St. Louis.

“Unless otherwise instructed, employees are expected to adhere to these principles and perform their responsibilities as outlined in all established policies and procedures. Should anyone be restricted from performing his/her responsibilities as a result of being listed on the exclusion list, please instruct the employee to immediately notify this office through their chain of command.”

Sgt. Keith Barrett offered an official statement on behalf of Police Chief John Hayden, saying, “The police division did receive an exclusion list created by the Circuit Attorney’s Office. While we are seeking legal guidance on how this affects the police division, we have also taken steps to notify each of the involved employees.”

Barrett then referred any further questions to Gardner’s office.

Follow Virginia on Twitter