Urinalysis to Determine Blood Alcohol in DUI Investigations

Urinalysis is the chemical analysis of a subject's urine. It has been used by police agencies in DUI investigations as a means of determining a driver's blood-alcohol level since long before breath testing devices came on the scene. It is still used in a few jurisdictions, usually as an alternative to breath or blood analysis, but it is today probably the least commonly encountered of the DUI test procedures. This is true for two reasons. First, taking a urine sample from a drunk driving arrestee is time consuming and, frankly, a distasteful job for the police officer. In jurisdictions requiring the sample to be taken at a hospital or laboratory rather than by the officer at the station, it involves considerably more time and trouble than a quick, on-the-spot breath test.

The second reason for the relative unpopularity of urinalysis is, quite simply, that it is the least accurate and reliable of the three methods of blood-alcohol analysis used in DUI cases. As researchers at Duquesne University have concluded, "the unreliability of using a urine ethanol concentration to predict a blood ethanol concentration cannot be questioned." Winek, Murphy, and Winek, The Unreliability of Using a Urine Ethanol Concentration to Predict a Blood Ethanol Concentration, 25 Forensic Science International 277, 280 (1984).

Dr. Kurt Duhowski, probably the most recognized blood alcohol expert in the country, prepared a document for the U.S. Department of Transportation entitled Manual for Analysis of Ethanol and Biological Liquids. That document concluded that:

"The only urine specimen which could, in theory, be confidently employed for alcohol analysis for purposes of estimating the co-existing BAC is ureteral [i.e., from the urethra] urine clearly an impractical specimen for law enforcement purposes. In summary, in the living human subject, only blood, saliva and urine are potentially usable specimens in law enforcement practice; of these only blood is sufficiently free of forensicallydisabling disadvantages and contradictions to be a practical specimen material for routine applications."

Similarly, the National Safety Council's Committee on Alcohol and Drugs (Ad Hoc Committee on Testing and Training) has recommended in DUI investigations that:

"Because of various problems in the interpretation of the results of the analysis of urine specimens for alcohol which cannot be readily overcome in law enforcement practice, urinalysis of urine for the purpose of determining blood alcohol is to be discouraged except under the strictly controlled conditions employed in determining renal [i.e., kidney] solute clearances."

Most forensic criminalists called by the prosecution in a DUI trial will be familiar with the studies and recommendations of the Department of Transportation and the National Safety Council, as well as the works and expertise of Dr. Dubowski. They will also acknowledge that many states have now repealed legislation authorizing the use of urinalysis in drunk driving cases.

The theory underlying urinalysis in a DUI case is simple. Alcohol is secreted by the subject's kidney by diffusion into the urine. The concentration of alcohol in the urine at the time of secretion in the average person is about 1.33 times the concentration of alcohol in the blood at the same time. Therefore, measurement of the alcohol in the recently secreted urine, followed by a simple computation, should theoretically give the subject's blood-alcohol ratio.

The urine sample is obtained necessarily from urine voided by the DUI arrestee. This represents urine that has been secreted by the kidney and passed into the bladder, where it sits until the subject urinates. Therefore, the urine that is being analyzed consists of a mixture of urine that has been secreted by the kidney over a period of time, at least since the last time the subject urinated. If the DUI suspect has not voided in 12 hours, for example, the specimen will contain a mixture of urine secreted by the kidney over that 12-hour period. In other words, the urine sample will not be indicative of the blood-alcohol level of the DUI suspect while he was driving within the past half hour or so, but rather probably will represent a chemical average of the level over the past 12 hours. Thus a man who had been drinking 8 or 10 hours earlier but who had "sobered" to a blood-alcohol level of zero by the time he was arrested for drunk driving, will produce a sample that clearly indicates - falsely - the presence of alcohol in his blood.

Chemical Evidence

The Lawyer's Guide to DUI Defense - Chemical Evidence

The Widmark Factor
Assumed values used in computing estimations of an individual's drinking pattern that are impressive to a jury but very susceptible to cross-examination.

Physiology and Blood Alcohol Analysis
Discussion of various factors affecting alcohol metabolism and blood/breath alcohol tests.

Dr. Michael Hlastala
Problems and issues with DUI blood-alcohol issues, from a noted professor of pulmonary medicine at the University of Washington.

Used in many states, often as a backup to breath or blood, urinalysis is a highly inaccurate and unreliable means of analyzing blood alcohol concentrations.

Homepage of the manufacturers of one of the more popular evidentiary breath machines used by law enforcement.

Intoxilyzer 5000
Manufacturer's homepage for another commonly used evidentiary breath machine.

Alcotest 7110/7410 Homepage for Draeger
Manufacturer of the latest and increasingly popular evidentiary and PBT devices.

Intoximeter EC/IR
Manufacturer's homepage for another new entry into the evidentiary breath testing field.

Breath Alcohol Testing Records (L.A. County Sheriff)
Online access to breath alcohol machine records, breath machine training/qualification of specific deputys and legal requirements of state law (Title 17) for administration of all breath and blood tests.

L.A. County Sheriff's Breath Machine Accuracy Records
Online access to the Department's accuracy and mainteneance logs for all breath machines, as well as usage logs and records of incomplete tests.

Website for manufacturer of blood specimen kits used by many law enforcement agencies.

Ignition Interlock Devices
Homepage for Guardian Interlock Systems, manufacturer of primitive and inaccurate "in-the-dash" breath analyzing unitsdesigned to prevent car ignition without a .00% breath sample, commonly ordered by courts as a condition of probation for repeat offenders.

CG Labs
Reanalysis of captured breath in New Hampshire and of blood nationwide.

Slope Detector
Why "slope detectors (designed to detect the presence of mouth alcohol in breath testing) don't work, from Dr. Michael Hlastala of the University of Washington.

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Forensic Toxicology Resources

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Lawyer's Guide Index

Urinalysis #1

Urinalysis to Determine Blood Alcohol in DUI Investigations

To avoid or at least minimize this problem of urine accumulation in a DUI case, it is necessary to have the subject void his bladder prior to producing a sample. After a short wait, perhaps 15 or 20 minutes, he should then be able to produce additional urine for analysis.

Certainly, urinalysis is a completely undependable DUI testing procedure where voiding has not taken place 15 or 20 minutes before the sample is obtained. In many jurisdictions today, this voiding is a legal prerequisite for admissibility of results in a DUI trial. (See, e.g., State v. Donaldson, 425 N.W.2d 531 (Neb. 1990), reversing a conviction where the sample was taken from the DUI defendant 33 minutes after voiding.) Where it is not, however, counsel in a DUI trial should move to suppress the results of urinalysis where the defendant was not required to void his bladder and wait before giving a sample. The reason for this is set forth by the American Medical Association in its publication entitled Alcohol and the Impaired Driver: A Manual on the Aspects of Chemical Tests for Medicolegal Intoxication (1968: American Medical Association, 535 North Dearborn Street, Chicago, Illinois 60610):

"If a person starts drinking with the bladder full of urine, or has not voided for some hours, while the blood level of alcohol is decreasing, the level in the bladder may change more slowly than that of the blood as the latter rises or falls. This discrepancy can be overcome by having the subject empty his bladder and by taking the sample of urine after 20 minutes."

In fact, obtaining only one sample of urine after a voiding is considerably less accurate than obtaining two samples isolated in time after a voiding. Although this is rarely done in DUI investigations by law enforcement agencies, counsel should at least bring out for the jury the fact that the American Medical Association, in the same publication, states (at p.71) that collection of "duplicate samples with a time lapse of at least 20 minutes and complete voiding of the bladder so that no residual urine is retained is recommended."

The AMA's recommendation has been endorsed by criminalists employed by the largest state prosecuting agency in the country. In an article entitled Blood Alcohol Concentration Determined from Urine Samples as a Practical Equivalent or Alternative to Blood and Breath Alcohol Tests, 30 Journal of Forensic Sciences 194 (1984), Biasotti and Valentine, two criminalists with the Bureau of Forensic Sciences, California Department of Justice, concluded after considerable research and experimentation that "[a] second urine 'sample' taken at least 20 minutes to one hour after first voiding the bladder should be used to determine an equivalent percent BAC." These criminalists went further, however:

"To validate further the accuracy of a BAC determined from the urine sample taken after first voiding the bladder, and to determine if the BAC has increased or decreased during the time between voiding and the second urine "sample," at least a 30-ml portion of the "void" urine sample should be collected, analyzed, and reported together with the second urine "sample" results."

Even where the proper voiding procedures were followed, urinalysis is at best a relatively undependable method of determining blood alcohol in DUI cases. Any honest prosecution expert witness, if pressed, will have to admit that of the three analytic procedures, urinalysis is generally considered a distant third in reliable accuracy. If he refuses to, his attention - and that of the jury - should be directed to a booklet entitled Highway Safety Program Manual No. 8. Published by the National Highway Traffic and Safety Administration of the U.S. Department of Transportation, the manual sets forth proposed regulations for the development and operation of alcohol testing programs. This is in accordance with Chapter 4 of Title 23 of the U.S. Code, known as the Highway Safety Act of 1966, wherein uniform highway safety standards are to be established. The following recommendations from that manual will be of interest to the jury:

"Because of various problems in the interpretation of the results of analysis of urine for alcohol which cannot be readily overcome in law enforcement practice, urine analysis to determine equivalent alcohol concentration in blood is discouraged, except under strictly controlled conditions (e.g., hospitalized subject), or for the limited purpose of demonstrating recent ingestion of alcohol. Chemical tests of blood or breath are preferred."

Urinalysis #2

Urinalysis to Determine Blood Alcohol in DUI Investigations

The procedures used to analyze a DUI suspect's urine are basically the same as those used to analyze his blood: gas chromatography, enzymatic reaction, and the dichromate or Kazelka-Hines method. There are a number of potential problems with each of these procedures; the dichromate method is nonspecific for alcohol, for example, and gas chromatography is subject to radio frequency interference.

As with all methods of blood-alcohol analysis, DUI defense counsel should consider first the training and qualifications of the individual obtaining the sample urine. In many jurisdictions, this person, whether a police officer or a laboratory technician, must have received specific instruction in the manner of collecting, preserving, storing, and transporting a urine sample in drunk driving investigations. If the individual has not received the requisite training, the test results may be inadmissible in the DUI trial. At the very least, the lack of training should be brought out for the jury's benefit to cast doubt on the accuracy of the test results.

The laboratory, too, usually must be properly licensed and/ or possess a current certificate of inspection for the DUI test results to be admissible. And the technician who conducted the analysis must have received the required licensing from the appropriate agency. Counsel in a drunk driving case should always bear in mind the ever-present possibility of gaps in the chain of custody of the urine sample. The prosecution has the burden of establishing the possession and control of the sample from the time it was taken after the DUI arrest to the time it was analyzed.

As with blood analysis, it is necessary to add some type of preservative to the urine specimen to prevent decomposition. If the specimen has been permitted to sit for a few days before it is analyzed, it will begin to decompose due to bacterial action. And decomposition can have an interesting side effect: the production of alcohol in the specimen from the decaying process. Refrigeration will serve only to slow down this decomposition, not to stop it altogether. To prevent this natural decay, a preservative such as sodium fluoride or mercuric chloride must be added to the urine sample.

Failure to add a preservative -and it is not at all uncommon - should provide counsel representing a DUI client with sufficient material at least to discredit the test results and possibly to prevent their admission into evidence. Even if a preservative has been added to the sample, there is no guarantee that bacterial action will not have taken place. There are many different types of bacteria that can be found naturally in urine; if they are of the aerobic variety, they will produce reducing substances in the urine that can raise the alcohol level in the urine before the preservative can be added.

Where there has been a urine void, the DUI attorney should not overlook the discovery possibilities. Many law enforcement agencies require the DUI suspect to place a sample from the void into a vial. This sample is then collected and stored along with the second test sample. A primary purpose of this practice is to prove that there was, in fact, a prior void. If such a void sample exists, it should be included in any discovery request and, along with the test sample, analyzed by an independent laboratory. Any significant variation in the two analytical results can prove extremely valuable as defense evidence:

1. A significant disparity between the two samples in a DUI case indicates unreliability of the analyses.

2. A lower void reading indicates a rising BAC.

3. A higher void reading indicates a lower true BAC (since the test sample theoretically consists of about 20cc of urine freshly secreted into the bladder mixed with 20cc of stale urine remaining after a void, the test result reflects a contaminated average of the two: avoid sample of. 12 percent and a test sample of .10 percent, for example, means that the BAC of an uncontaminated test sample would have been about .08 percent).