One defense to DUI that a criminal defense attorney may use is that the blood sample was not refrigerated properly at the hospital or during transportation. Sodium Fluoride and other chemicals are typically used to preserve the sample, but some say that even with preservatives, a sample left unrefrigerated for as little as an hour can cause an artificially high blood alcohol concentration (BAC). The idea behind this is that the blood becomes putrefied, where microorganisms that would otherwise die during refrigeration convert sugar in the blood into alcohol.
As logical as this concept seems, the science behind it may be flawed. Assuming the blood sample was properly drawn from the person, blood from a living person is completely sterile. That is, there should be no microorganisms in the blood for putrefaction to be able to occur. Perhaps even more convincingly, studies show that the BAC of unrefrigerated blood actually decreases over time. The reason for this is that after it is drawn and exposed to oxygen, red blood cells begin to convert the alcohol in the blood to acetaldehyde. Moreover, the higher the temperature, the faster this reaction occurs. In a recent study where blood samples were intentionally left in the trunk of a car (with temperatures ranging from 68º to 113ºF, to simulate being left in a police officer’s trunk), the samples’ BACs decreased as much as .015% over the course of a week.
Despite the science mentioned above, many criminal defense lawyers still employ the defense that the sample was not refrigerated in order to challenge the reliability of it. But it seems that if anything, an unrefrigerated blood sample will actually benefit the defendant. This area will likely remain a hotbed for litigation until additional, more conclusive studies determine the answers. You can read more about DUI and DUI defenses here.