Flow Sensor Calibrations: Why the Intoxilyzer 8000 Used for Florida DUI Breath Tests is Unreliable

Matthew Malhiot recently published an informative article discussing the Intoxilyzer® 8000: Flow Sensor Problems in Florida.

The article describes how Florida never bothered to develop any procedure for testing whether the Intoxilyzer 8000 instruments could accurately measure the amount of air blow into the machine. As a result, the instrument may have produced unreliable breath test results for thousands of individuals who agreed to submit to a breath test after a DUI arrest in Florida.

Problems with the Intoxilyzer 8000 Instruments Maintained by the Hillsborough County Sheriff’s Office Central Breath Testing Unit

In Hillsborough County, seven of the eight instruments have been tested and “calibrated.” The problems were so bad on some instruments that the flow sensor was actually replaced. The only remaining instrument yet to be tested in Hillsborough County is still in being used to test subjects after a DUI arrest although those results should certainly be contested based on the serious problems that existed on the other machines.

What Did FDLE Know About Flow Sensor Problems and When?

The problem was so bad that even the Florida Department of Law Enforcement (FDLE) stepped in to remove at least one instrument in Hamilton County from evidential use in 2009 after problems with the way the machine measures the volume of air blow was detected. Despite knowing that the problem likely existed in other instruments, FDLE allowed other counties to continue using the instruments until each one could be “calibrated” by FDLE.

Matthew Malhiot reports that beginning in 2009, FDLE purchased the equipment to begin testing for flow sensor accuracy. Although FDLE went to the trouble to purchase the equipment to test the accuracy of the flow sensor, that equipment sat on a shelf in Tallahasse unopened. Although FDLE’s written procedures had no provisions for inspection of flow sensors, Matthew Malhiot reports that the was the only FDLE Department Inspector who began his own attempts at testing whether the flow sensors were able to return accurate readings. FDLE did not implement any “informal” procedure for testing the flow sensors until August of 2010. The way those tests are being implemented is largely a mystery to criminal defense attorneys who have access to nothing other than field notes and repair records showing the fact that the flow sensors had to be “recalibrated” or replaced with new parts.

Problems with the “volume” reading do not show up in the departmental and agency inspections developed by CMI, Inc., and FDLE for Florida’s version of the Intoxilyzer 8000. In fact, the departmental inspections and agency inspections were developed in a way that avoiding testing whether the flow sensor worked. Despite the fact that it is not hard to imagine that such a testing procedure could have been included in the administrative rules or written protocol developed by FDLE.

Secret Mathematical Calculations Within the Machine

The company that manufactures the Intoxilyzer 8000 calls the flow sensor a “pressure transducer” which takes data points showing the sample duration and pressure to estimate a flow rate. Through an unknown mathematical calculation those data points are translated into a volume reading. An accurate Breath Alcohol Calculation (BrAC) relies on a sufficient volume of air being introduced into the instrument during a sample. If the volume is not accurate or reliable than the BrAC reading cannot be accurate and reliable. Florida decided to set the minimum volume requirement at 1.1 litters of air (although other states were allowed to set slightly higher or lower requirements for this “conforming product”).

As we have previously discussed, the top FDLE officials including Roger Skipper and Laura Barfield claim not to know who manufactures the pressure transducer because they have never looked at the logo or cannot remember what the logo says. FDLE has no idea how many times CMI, Inc., has change or modified the type of the pressure transducer being used. It is unclear whether different instruments in Florida even have pressure transducers from the same third party manufacturer or whether those pressure transducers are even compatible with a breath test instrument like the Intoxilyzer 8000.

If the Flow Sensor Does Not Give Accurate and Reliable Readings then No Readings From the Machine are Accurate or Reliable

These problems mean that certain instruments incorrectly assumed that an individual who blew less than the required 1.1 liters of air had provided a sufficient sample. In other words, if you blew less than 1.1 liters of air during a sample the instrument may have incorrectly assumed that the sample was sufficient. The machine is not suppose to flag an error for any sample that is less than 1.1 liters of air which would not occur if the flow sensor was not working correctly.

It is also likely that individuals who provided a sufficient sample registered a “volume not met” reading even though a sufficient reading was provided. Those individuals may have been told that they “refused” to provide a sufficient sample when the real problem was that the the flow sensor did not work properly. Those individuals were most likely charged with “refusing” to provide a sample and were hit with an automatic one year revocation of their driving privileges in Florida.

If the flow sensor does not work properly then all of the other readings made by the instrument should also be questioned including whether slope was level or slope was met. If the flow sensor did not work properly then the instrument would not be able to correctly determine whether the reading was from “deep lung” air or merely from trace amounts of “mouth alcohol.” Individuals with acid reflex, dentures, GERD, or a number of other conditions may have returned high readings that were not accurate or reliable. Individuals with smaller or diminished lung capacities because of their age or health conditions are more likely to be impacted. Women typically submit lower volume readings and the inherent bias in the instrument against women would also be more pronounced due to this issue with the flow sensor.

Losing Faith in Florida’s Alcohol Testing Program Hurts Us All

At some point FDLE takes so many shortcuts and is involved in so many scandals and cover ups that the public loses any faith in Florida’s Alcohol Testing Programs. Innocent people arrested for DUI refuse to take the test because they know the machines do not work. Juries refuse to rely on breath test readings from the machines because of the evidence presented at trial showing these serious problems. Prolonged litigation over these issues and FDLE’s instinctive need to cover up the problem drain our criminal justice system of precious resources. The judges that must determine whether this evidence should be admitted at trial begin to question whether the instrument actually works, whether the administrative rules are adequate, and whether agency and departmental inspectors can be trusted.

FDLE and the manufacturer of the instruments have engaged in a course of conduct that involves hiding the evidence of a problem for as long as possible, losing the evidence once the problem is discovered, and arguing that the problem does not effect the accuracy or reliability of the instrument because of some “excuse” that cannot be proved or disproved without the evidence that has been hidden or destroyed. As judges are beginning to recognize the true extent of the problem more and more breath test readings will be excluded from trial. The problems with the flow sensor may just be the straw that breaks the camel’s back.

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