Here's the latest on the saga of Vermont's malfunctioning DUI breath-testers:

After months of saying next to nothing about the embarrassing episode, state prosecutors have finally filed their official response to claims that the breath-testing instruments Vermont uses to convict drunk drivers cannot be relied upon.

The response comes in a court filing in a Washington County drunk driving case. The case exposed flaws in state health lab's handling of the instruments and led to dozens of DUI cases getting dismissed or bargained down to lesser charges.

In a 15-page motion, state prosecutors argue that the DataMaster DMT (pictured), the infrared breath-tester used in Vermont since 2008, is dependable technology that has been approved for evidentiary use by everyone who has scrutinized it — the courts, the National Highway Traffic Safety Administration, even the state chemists whose complaints about the instruments exposed the problems in the first place. While acknowledging recent missteps, the state argues that the machines themselves are dependable and received all necessary approvals from state officials before being put into use.

But the lawyer challenging the state's handling of the breath-testers says that's not true — and that the failure to get sign-offs throws DUI convictions into question.

Criminal defense attorney David Sleigh is challenging the DataMaster on behalf of a client facing his fifth DUI. Sleigh has asked the judge to toss the breath-test used to arrest the man. His case rests in part on a loophole: Sleigh says the state health commissioner never approved the DataMaster DMT when it was first deployed to Vermont police agencies, as required by state regulations. Sleigh says the only approved instrument is the BAC DataMaster, the DMT's predecessor, and argues that should automatically exclude evidence collected on the new machines.

But Deputy State's Attorney Stuart Schurr rejects that argument, noting that two health commissioners approved "the DataMaster using infrared technology" — in 2006 and again in 2010. In the court filing, Schurr argues that the old DataMaster and newer version are so similar in engineering and design as to make re-approval unnecessary.

"All DataMaster instruments, both present and future, were approved by the commissioner on February 7, 2006, thereby obviating the need for subsequent approvals," Schurr writes in the filing.

Sleigh says that's not true and that the National Highway Traffic Safety Administration indicated as much when it required the DataMaster's manufacturer, Ohio-based National Patent Analytical Systems, to submit the DMT for testing before placing it on the list of "approved devices" for evidentiary breath-testing. The BAC DataMaster, which Vermont had used since the late '80s, was already on that list.

"My argument is that you can't approve a brand," Sleigh says. "You have to approve a device and there's no evidence that the commissioner ever approved the DMT."

Sleigh is also arguing that recent events have shown that, in the hands of state health lab employees, the instruments cannot be considered reliable in any case — regardless of whether a specific instrument has exhibited problems. In response, Schurr writes that systemic problems aside, Sleigh's client has failed to raise "any alleged deficiencies with this instrument, on this date, when analyzing this breath sample."

Schurr goes on: "The evidence will demonstrate that the instrument used to analyze Defendant's breath sample on May 23, 2010, was operating properly, produced accurate and reliable results, and met or exceeded each and every one of the 'performance standards' set forth in Department of Health regulations."

The case in question is something of a test case. If Sleigh can persuade the judge that problems at the state health lab make his client's breath-test results inherently unreliable, lawyers all over Vermont could start pointing to that ruling to get their own clients off — or at least create enough reasonable doubt to bargain down the charge to something less than DUI. The reverse is also true: If the judge upholds the DataMaster's reliability, it could be much harder for people charged with DUI to argue that the technology is unreliable.

The judge is expected to issue a ruling in the case in the coming weeks.