Twelve years ago, a city report on the narcotics unit concluded it was "critical" to rotate officers out of the unit, but despite support from the city, the proposal was never implemented.
The union has fought time limits for serving in narcotics, arguing that experience in the unit allows officers to become more skilled and specialized, and build better relationships with informants.
"There are 200 officers in narcotics who do a lot of good work," McNesby said Wednesday. "Accusations - and I'll call them accusations - against six officers should not tarnish the whole unit."
Ramsey said the rule governing the transfer of officers in specialized units was "one of the most restrictive I've ever seen when it comes to moving personnel."
The department may transfer officers from specialized units only for disciplinary reasons, or if officers are needed to fulfill "essential manpower requirements" in other units.
One of the officers arrested Wednesday, Thomas Liciardello, was found to have violated department policy by conducting an illegal search in 2005. Ramsey, who joined the department in 2008, said that because he did not handle the case, he could not comment on whether that violation would have allowed police brass to transfer Liciardello.
The decision to discipline officers by removing them from their units is made on a case-by-case basis, Ramsey said, and in some instances, arbitrators overturn the transfers.
Liciardello and five other officers were moved from the narcotics unit in 2012 after District Attorney Seth Williams told Ramsey that his prosecutors would no longer call on the officers to testify in drug cases.
McNesby said the union continued to oppose rotation. He said the department has safety nets in place to safeguard against corruption.
"They already had to have a background check to get into narcotics," he said. "You have plenty of supervision, a disciplinary system in place, and a commissioner who is obviously not bashful about firing people."
Ramsey said he hoped that Wednesday's arrests would "give us what we need" to change the policy."
"We need to be able to move people from these sensitive units," he said, "if there's any hint at all that they are engaging in misconduct."