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We’re Stacy Cowley and Jessica Silver-Greenberg, reporters for The New York Times. We investigated how legal and forensic flaws in alcohol breath testing have led to the dismissal of tens of thousands of tests in recent years. Ask us anything.

On this week’s episode of The Times’s TV show “The Weekly,” we looked into lawsuits in multiple states — including Colorado, Massachusttes, New Jersey and Washington — that called into question the reliability of the breath tests used to prosecute drunk drivers. The science behind the tests is generally sound, but human errors and lax oversight have led to some catastrophic mistakes. In Massachusetts and New Jersey alone, more than 30,000 tests that led to convictions have recently been tossed out because the tests were unreliable.

That cuts both ways. Potentially innocent drivers have been punished based on faulty tests. But when large batches of tests are dismissed, it becomes much harder for prosecutors to convict dangerous drivers and keep them off the road. You can read our full investigation here.



UPDATE 12:30pm: Thanks everyone! We're signing off for now but will check back later to catch a few more questions.

November 7th 2019
interview date

What do you think about CMI not making their "Intoxilyzer 9000" available for independent scientific research to anyone not affiliated with law enforcement?


We found the secrecy by all the manufacturers--not just CMI--to be pretty unusual. The companies have imposed very stringent requirements on anyone who wants to get a look under the hood of these machines.

One of the hackers in Washington state had done very sensitive work for Microsoft, and he said that the demands by Drager were tougher than that!

“I worked on the most confidential things that Microsoft does, and they don’t have any procedures like this,” Robert Walker told us during an interview.

Judges are starting to catch on. They have blasted the manufacturers and the states for their extraordinary secrecy. Florida, a panel of judges described their state’s instrument as a "magic black box" with “significant and continued anomalies.”



I was surprised that the police officer in your Weekly episode said something like "I'm fine after 7 beers," meaning he would still be under the legal limit. Is that typical? Does he have an unusually high tolerance?


We found that .08 is, for most people, a pretty high limit! Everyone's physiology is different, but 1-2 drinks really won't put most people up at that mark — it generally takes a fair bit more before you're at the .08 limit. It can be eye-opening to try out a portable breathalyzer and see what you personally blow after a few drinks. (We, um, MAY have experimented a bit with this during our reporting.) -Stacy


Is this movement a new thing? How long did it take them to notice and why didn't they notice? I know for a long time in Massachusetts a common way to get breathalyzer results thrown out of court was to question the calibration of the machine. A lawyer friend of mine said it has worked for him more times than it has not.

How do you think this will effect people like that driver who killed a bunch of motorcyclists in Nh over the summer?


Lawyers have been playing whac-a-mole with breath test results for decades -- they'll question *everything* about the test in an effort to find a mistake that can get it DQ'd. It drives prosecutors nuts, but many also acknowledge that the defense bar is a useful check-and-balance -- the systemic problems that have come to light in various states generally only did so because relentless lawyers found something that seemed off and kept digging.

Cases that led to serious injury or death are typically given extra levels of care and scrutiny by police and prosectors. It's rare in those cases for a breath test to be the only evidence of intoxication. In the end, it still all comes down to a judge or jury (or a guilty plea), but those cases are typically treated very seriously. -Stacy


Stacy and Jessica, excellent reporting. I'm curious - in your investigation to how these breathalyzers work, did you find any evidence as to how 0.08 became the standard?

To add on to that, has anyone addressed the personal variation in intoxication? It's a well-known fact that some people show signs of intoxication at 0.04, whereas chronic alcoholics may not show any signs of intoxication until 0.20 or above!


States started moving toward it in the '80s and '90s, but it became a de-facto standard in 2000, when President Clinton and Congress passed a law that tied it to highway funding -- to get the cash, states had to move to the .08 standard. Every state eventually did.

And the issue of "personal variation" comes up a lot in discussions about DUI laws. As you noted -- the point at which a person becomes impaired can vary a lot. The .08 standard was intended to cut through that and designate a mark at which everyone was considered too intoxicated to drive, regardless of whether they actually appeared impaired or not. -Stacy


What is the number 1 flaw of the breath testing?


Human error. By far. These are scientific instruments that have to be calibrated correctly, maintained correctly and used correctly. When something goes wrong in that process, the result becomes unreliable. Nearly all of the cases we found where large batches of cases had to be throw out were because someone made a mistake in the calibration or maintenance process. -Stacy


Is there a scientific body that is in charge to validate these machines on a schedule? Should there be?


The federal auto safety regulator, National Highway Traffic Safety Administration, maintains what's called the "conforming products" list of approved breath-testing machines. It's a register of devices that have passed their own tests and are considered generally reliable. But states are expected/encouraged to do their own additional testing, because the NHTSA tests don't catch everything.

Beyond that, every state sets their own rules about how their tests will be done and how their devices will be set-up and maintained. Some have pretty strict rules (which, we found, aren't always followed); some are very lax.

One interesting development: The Massachusetts state lab we wrote about recently became accredited by the the ANSI National Accreditation Board. Only a handful of state breath-testing programs have sought out accreditation, but it's a good step toward ensuring that scientific protocols are established and followed. -Stacy


I haven't read the article yet, doing so now, but is this during a police stop or issues with breathalyzers you purchase and take yourself?

What steps would someone take if they felt there was a problem?

Unrelated to these questions, I had a terrible time with a stop once. I didn't want to submit to the test on the road so they took me to a place with a machine. They said I didn't breath correctly (uh) and then gave me a gigantic bruise drawing blood. It ended up being under the limit. Thanks, county.

In the middle time I just had a pub defender basically try to talk me into pleading guilty because I'd have to pay $1000 to get the bloodwork done if not. This took months because the lab was backed up, as I assume it is all of the time. I waited and was fine. The system really craps on people who can't afford to fight it.


First of all, I'm so sorry to hear you wound up with a gigantic bruise. Second, our investigation zeroed in on the tests administered at the station, not the roadside one.

Roadside tests, which rely on fuel cell technology, are widely acknowledged to be pretty finicky. All sorts of things can trigger a false positive, including burping or breath mints. That's part of the reason why in most states they are not admissible in court.

We decided to focus on the tests at the station, partially because those were marketed as being reliable to the third decimal place. We found out that was not true.



is there a better alternative to this seemingly outdated technology?


Blood tests are the gold standard, but they have their own risks. Sometimes, police officers end up injuring motorists trying to reach a vein. But the biggest issue with them is that they require a warrant.



Is it hard to overthrow a conviction where a driver fails a field sobriety test and when they do a blood test, it shows positive for marijuana that was used hours before the traffic stop?


That's definitely a question for a lawyer. Marijuana is a hot issue right now in DUI enforcement -- there's a gold-rush mentality among makers trying to develop a reliable roadside screening method for it, but so far, the options out there generate LOTS of false positives. -Stacy


With legalization of Marijuana in Canada, law officers are looking for ways to catch intoxicated smokers behind the wheel. Is there any future where a breathalyzer type of test is possible to catch Marijuana users?


That future is now. Manufacturers are already rolling out tests to detect drivers who are under the influence of marijuana. So far, when analyzed some of those machines have registered some false positives. A test in Canada found that poppy seed bagels threw off the tests.



I've heard for a long time that you should refuse all tests, take the alternative (usually arrest) and fight it in court.

What are your thoughts/advice on this approach?


It's an approach that has its own set of risks. Lawyers have advised drivers to do exactly what you are describing, but all 50 states punish drivers who refuse to take the test--some very harshly.


If I were to be breath tested what should I look for to identify if a test is being performed incorrectly?


In most states, you get a printout of your test results. This is the results page for Matt Mottor, the driver we wrote about in our story:

The results are kind of inscrutable to a lay person, but a knowledgeable lawyer or scientist in the field can go through the info and other records on the machine used -- like when it was last calibrated, its repair records, etc -- and look for irregularities. -Stacy


What made you investigate this matter?


We noticed some litigation in local courts across the country, and we wondered if it was a national issue. As we were investigating, the cases in Massachusetts and New Jersey started blowing up.


Through your reporting do you have an opinion on whether the standard .08 should be higher or lower?


Utah became the first state to knock down the standard to .05. And New York has been kicking around legislation to follow their lead. MADD, perhaps unsurprisingly, has mounted an aggressive citizen lobbying campaign to push states to lower the standard to .05.



Did you compare US situation to any other country? I'm finnish and here afaik the breathalyzers are considered reliable. Works great if the laws and usage is done right.


We focused our reporting on the United States, but many of the manufacturers distribute their machines--the same ones that we looked at--around the world.



Have there been any successful "cheats" found to beating the breath tester? E.g. the old classic sucking on pennies.


The manufacturers are on to you! The technologies have improved a LOT in the past decade, and get fooled less than they used used to by interfering substances and such. The tests are also hard to trick. The pennies thing is definitely a myth. -Stacy


What are states doing about marijuana?


Trying hard to figure it out! A bunch of manufacturers are trying to develop reliable roadside tests, but so far, they're really flaky. Enforcement right now relies heavily on cops to make the case that a driver is impaired.

The growing use of dashboard cameras and body cameras have helped there -- it's now easier for judges and juries to see the behavior and actions of a driver that a police officer says is intoxicated or high. -Stacy


How do you feel about you work potentially absolving someone that was committing a dreadful crime that could (or perhaps did) result in someone being severely injured or killed?


Our goal in this story was to expose the problems with the machines so that governments, police officers, lawyers and the general public would have more information.

We found that it was the problems with the machines, not our reporting, that has already led to potentially dangerous drivers getting back on the road. For example, when Massachusetts discovered flaws, their solution was to toss out tens of thousands of breath tests. With their tests, invalidated, repeat drunk drivers went free.

Here's some who are back on the road: A man who slammed his car into an 83-year-old woman outside a liquor store and then failed field sobriety tests. A man who was puking out the window and veering “all over the road.” And a third who had a suspended license and then blew at .32--a level of drunkenness that would leave most people unconscious or in a coma.




Do you have interest in looking at other test police and prosecutors use to convict innocent drivers such as the questionable accuracy of Horizontal Gaze Nystagmus test?


I sat in on a CLE class for lawyers were the field sobriety tests were discussed -- they range quite a lot in their reliability, and depend on a trained cop to do them correctly. It's an area lawyers often attack in defending DUI cases. -Stacy




Here's a way to find out: google.