Archive for September, 2007

How Do You Know the Blood They Tested Was Yours?

Monday, September 10th, 2007

Let me tell you about one of my law firm’s cases that ended up in a Los Angeles Times article entitled "DUI Case Botched by Blood Mixup".

One of our attorneys had a young client who had been arrested for drunk driving by the Los Angeles Police Department and had a blood sample drawn from his arm. He swore to us that he was innocent, and we believed him. Problem: the blood alcohol content of the sample was .15% — almost twice the drunk driving limit.

Now what?

We obtained a portion of the sample from the LAPD crime lab and sent it to a private lab that we use for reanalyzing the blood samples of all our DUI clients. The lab reported the blood alcohol level to be .13% lower, but a long way from being under .08%. As we requested, they also tested for preservative and anticoagulent (either fermentation or coagulation can raise the alcohol level in the sample), but everything appeared in order.

Our client still insisted he was not driving under the influence of alcohol. The only other possibility was a faulty chain of custody. In other words, the LAPD lab (the same one that botched the O.J. Simpson case) got the vial of our client’s blood mixed up and tested someone else's blood. 

So we had the sample blood-typed to see if it was that of another arrestee. Result: type “O”– the same as our client’s. But, then, that's the most common type of blood.

We decided to try something different, something that, to our knowledge, had not been done before in any DUI case. We had blood taken from our client and, with a portion of the remaining sample from the LAPD lab, shipped to a laboratory in Oklahoma that specialized in DNA testing.

A month or so later the report came in: the blood tested by LAPD was conclusively not that of our client.

The prosecutor in the case initially refused to accept these results. But after we proved that the comparison blood had come from our client and after LAPD checked the blood themselves, he reluctantly dismissed all criminal charges. Predictably, in the L.A. Times article LAPD tried to point the finger at someone else:


Police officials said they are investigating how the mix-up occurred and who is responsible, But, they said, they are fairly confident that the lab did not make a mistake. One possible explanation, they said, was that the blood was mistakenly labeled when it was initially drawn by nurses at LAPD’s jail intake facility in Van Nuys.


As always, the police claim infallibility: “We do not make mistakes…It was the nurses”.

So how could this have happened? The truth is that it probably happens far more commonly than you suppose.

When a blood sample is drawn from the suspect in a DUI case rather than using a breath machine, the sample is supposed to be inserted into a vial containing preservative and anticoagulent, then shaken and sealed. Procedures require that a chain of custody be established: the location of the vial of blood must be identifiable at all times so that it does not become contaminated or mixed up with someone else's vial. This is done by labelling the seal with identifying information, then usually placing the sealed vial in an evidence locker (which should be refrigerated but often is not) until it is transported to the crime laboratory for further storage and refrigeration. At any stage of this chain of custody, of course, things can go wrong with the vial or the records.

It may be a week or so before the vial is finally analyzed. This is commonly done using gas chromatograph instruments, and the vial is one of many analyzed in large “batches”. A batch is a group of vials, perhaps 40 or more which are analyzed in sequence; this is much faster and more economical than isolating, identifying and separately analyzing one vial after another. Of course, it is critically important that the sequence of vials tested by the gas chromatograph coincide with the sequence of vials in the records. If the sequence of numbering of the vials is off by one, then the records will show a result from the analysis of another vial. And it won't be just one person whose blood is falsely reported: every other vial may also be one off — and will all be wrong. And you have 40 people people facing criminal charges based upon false evidence.

“How do I know the blood they tested was mine?” Simple – if you can get a portion of the sample from the crime lab and have an extra $1200 for DNA testing laying around.

Otherwise, I guess you'll never know.

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Secret Breathalyzer Software Finally Revealed

Tuesday, September 4th, 2007

As I've indicated in previous posts, defense attorneys for years have been trying to discover the software source code used by manufacturers of various breathalyzer models.  (See "Secret Breathalyzer Software Still Secret")   The accuracy of these  machines, which essentially determine a suspect's guilt or innocence, depends upon the accuracy of the software driving them; as the computer techs say, "Garbage in, garbage out".  But the manufacturers have refused to produce the information, relying upon a claim of "trade secrets" — that is, that the code of each model is a unique creation of the manufacturer.  And prosecutors, apparently more concerned with profits than with justice, have joined them in resisting disclosure.

Recently, however, judges in Florida, Minnesota, New Jersey and a growing number of other states have begun ordering the manufacturers to reveal the inner workings of their machines to the defense.  (See "Judge: Divulge Breathalyzer Code…or Else".)  Not surprisingly, the manufacturers have refused to comply.  Until a few days ago….

New Jersey attorney Evan M. Levow was finally able to get an order from the Supreme Court of New Jersey forcing the manufacturer of the popular Draeger AlcoTest 7110 to reveal the source code.  Levow turned the code over to experts, Base One Technologies, to anaylze.

Initially, Base One found that, contrary to Draeger's protestations that the code was proprietary, the code consisted mostly of general algorithms:  "That is, the code is not really unique or proprietary."  In other words, the "trade secrets" claim which manufacturers were hiding behind was completely without merit.

Some of the more interesting excerpts from the Base One report:


 1. The Alcotest Software Would Not Pass U.S. Industry Standards for Software Development and Testing: The program presented shows ample evidence of incomplete design, incomplete verification of design, and incomplete "white box" and "black box" testing. Therefore the software has to be considered unreliable and untested, and in several cases it does not meet stated requirements. The planning and documentation of the design is haphazard. Sections of the original code and modified code show evidence of using an experimental approach to coding, or use what is best described as the "trial and error" method. Several sections are marked as "temporary, for now". Other sections were added to existing modules or inserted in a code stream, leading to a patchwork design and coding style…

It is clear that, as submitted, the Alcotest software would not pass development standards and testing for the U.S. Government or Military. It would fail software standards for the Federal Aviation Administration (FAA) and Food and Drug Administration (FDA), as well as commercial standards used in devices for public safety…If the FAA imposed mandatory alcohol testing for all commercial pilots, the Alcotest would be rejected based upon the FAA safety and software standards…

4. Catastrophic Error Detection Is Disabled: An interrupt that detects that the microprocessor is trying to execute an illegal instruction is disabled, meaning that the Alcotest software could appear to run correctly while executing wild branches or invalid code for a period of time. Other interrupts ignored are the Computer Operating Property (a watchdog timer), and the Software Interrupt.

6. Diagnostics Adjust/Substitute Data Readings: The diagnostic routines for the Analog to Digital (A/D) Converters will substitute arbitrary, favorable readings for the measured device if the measurement is out of range, either too high or too low. The values will be forced to a high or low limit, respectively. This error condition is suppressed unless it occurs frequently enough…

7. Flow Measurements Adjusted/Substituted: The software takes an airflow measurement at power-up, and presumes this value is the "zero line" or baseline measurement for subsequent calculations. No quality check or reasonableness test is done on this measurement…

10. Error Detection Logic: The software design detects measurement errors, but ignores these errors unless they occur a consecutive total number of times. For example, in the airflow measuring logic, if a flow measurement is above the prescribed maximum value, it is called an error, but this error must occur 32 consecutive times for the error to be handled and displayed. This means that the error could occur 31 times, then appear within range once, then appear 31 times, etc., and never be reported…


Based upon a .08% reading from this machine, American citizens are accused of drunk driving and, in court, presumed by law to be guilty.

 

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