Blood tests in hospitals are perfectly fine for use in diagnosing diseases and treating patients. However, when it comes to their use in forensic tests for prosecution purposes, they are bad. The manufacturer of the blood test analyzing machines specifically states that the tests are for diagnostic use only. Hospitals do not follow forensic testing procedures or international standards of measurement. At best they are a guess of what the alcohol level may be. A doctor does not care if a blood test results is a .07 or a .09. If it is a .14 or a .17. Doctors just want to know that there is alcohol in a patient and approximately how much so they know how to treat the patient. However, the law does. The difference between a .07 and a .09 is jail. The difference between a .14 and a .17 is a lot more jail and all of the things that go along with being convicted of a DUI in Pennsylvania.
To understand the multitude of problems that are inherent in hospital based blood tests it is important to know what is actually tested and measured. Alcohol is not what is measured. That is right. Alcohol is not what is measured. What is measured is NADH. Therefore, hospital based blood tests are indirect tests of alcohol. This testing process is an enzymatic based reaction of several compounds, including alcohol, that produces NADH. NADH is in a one to one ratio with alcohol. However, many things can form NADH. Lactate and lactic acid are two things that will read as NADH in these tests. Furthermore, whole blood, which is blood with all of the solids and liquids, is not tested. What is tested is just the liquid part of the blood which is called serum and plasma. The difference between the two is very slight so I will just refer to what is tested as serum. To get blood serum the test sample is spun (centrifuged) removing all of the solids. The solids must be removed because hospital analyzers use a light absorbance method called spectrophotometry. In this process, a light in the purple spectrum is focused on the sample and its absorbance is what is measured. Since whole blood is dark red due to the red blood cells this process could not be done on whole blood. That is why the solids are removed and the clear serum is tested.
Since a lot of traffic accident cases have hospital blood test results, the fact that lactic acid and lactate can be read as alcohol is very problematic. In most of Pennsylvania, hospital blood alcohol tests show up when there are serious bodily injuries or deaths involved. Since Aggravated Assault While DUI and Homicide by Vehicle while DUI are felonies in Pennsylvania and the punishments are harsh, it is very alarming that a lot of the blood test results in these cases come from a method that is forensically indefensible. Yet prosecutors all over Pennsylvania still use hospital blood test results and rarely question them. They have to be forced to see the many faults in these tests.
There are many other issues with hospital blood tests in Pennsylvania Alcohol DUI cases. The list is long and this blog could go on for pages but I will just summarize a few more of them. International forensic and measurement standards followed by the Pennsylvania Crime Labs and private labs like NMS are not followed by hospitals. The reason they are not is because these are clinical labs. Clinical labs are designed for taking care of patients, not to follow the rigorous standards of forensic testing. Doctors need test results fast. Following forensic standards is a slow process. Fast is not conducive to accurate. Things like chain of custody, daily calibration of the instruments, traceability to a national standard of all components used in testing for blood alcohol content, and the reporting of uncertainty are not something hospital labs are designed to follow. These issues are well known in clinical hospitals. Most hospitals in PA are audit by the College of American Pathologists. Their very own manual states that hospital blood tests should be confirmed and the labs should follow forensic procedures. I know this because I have the manual and use it in court.
All of the issues mentioned previously contribute to the uncertainty of the test result, Then, once there is a test result it must be converted to a whole blood equivalent. The reason it has to be converted into a whole blood equivalent. This is because Pennsylvania DUI law requires a whole blood test result in court. A conversion factor is used because as I wrote previously, serum has a higher alcohol content than whole blood so it needs to be converted down to a whole blood equivalent. The problem is what conversion factor to use? There are many. It is scientifically invalid to use one number as a conversion factor because it is well known that the solid to liquid ratio in blood varies from person to person and varies within a person from hour to hour so a range of conversion factors must be used. But which range. Prosecutors like narrow ranges despite published studies that show a conversion factor of percent to 47 percent is valid based on studies done of over 200 hospital patients.
When it comes to drug tests in hospitals it is even worse. What is usually tested is urine. Urine tests are screening tests. The manufacturers of the urine testing kits specifically say this. Furthermore, urine tests only show if a urine sample is positive or negative for a drug. It does not give levels, even if blood is tested for drugs, hospital drug tests are still screening tests. They too only show positive or negative test results. Furthermore, these hospital drug tests can’t differentiate between the active compounds that cause impairment and the inactive metabolites that do not. Not to mention that urine test results, even if tested in forensic labs, can’t be related to impairment. At best they can be used to show that drugs were used in the past.
Fortunately, Pennsylvania DUI laws do not allow urine or blood screening test results into evidence for use in the per se Pennsylvania DUI Drug offenses. It is also very hard to get them into evidence for use in prosecuting the drug impairment related charges.
In summary, the hospital based tests used to prosecute Pennsylvania drug and alcohol DUI offenses are fraught with problems, and a lawyer who understands them can use that knowledge to great advantage in defending people charged with DUI. I once had a DUI case in Bradford County where my client was in a roll-over accident. The test results showed the presence of cocaine, marijuana, and a .2 plus blood alcohol content. So prior to the preliminary hearing I called the hospital lab and asked them the drug screening test they used. They told me. I then got the manufacturer’s product insert. I took this to the preliminary hearing and showed them the limitations of this test. That and how they could not determine who took the blood and urine samples the case was withdrawn. My client had a long record and it was a second offense. So she was saved from a possible state sentence.