A blood draw in lieu of a breath test is an option available in many states. Blood draws, when performed properly, are generally a more accurate. However, even if the blood draw is an “option," it may not be your option!
In many states, including the State of Washington, a blood draw is an alternative to a breath test if you are under arrest for vehicle homicide, vehicular assault, if you are unconscious (and were arrested for DUI, physical control, or minor under the influence), or a DUI arrest resulting from an accident with serious bodily injury. The other way that a blood draw may be administered is if you are physically unable to provide a breath sample (ie. asthma, emphysema).
States usually require that no person than a physician, registered nurse or a phlebotomist qualified by the state can draw the blood for purposes of determining the alcohol concentration. However, there is a move afoot where some states are experimenting with allowing law enforcement to administer blood draws. I personally cannot think of anything more frightening that having an angry and perhaps medically unqualified law enforcement officer drawing blood from my arm. However, it would also be ripe for legal attack. Each state has specific guidelines stating how these tests are to be taken, transported, preserved, secured, and analyzed.
Such guidelines and procedures must be used to collect the blood sample, otherwise the blood analysis will be flawed. For example, the American Medical Association suggests the following procedures:
Hypodermic needles and syringes (must) be sterile and disposable. When reusable equipment is utilized, it should neither be cleaned with nor stored in alcohol or other volatile solvents.
Only a chemically cleaned, dry tube or vial with inert stopper should be used. Neither alcohol nor volatile solvents should be used to clean them. The tubes and vials should contain an anticoagulant (recommended are fluoride, citrate, oxalate and heparin), and a preservative (recommended are fluoride and mercury salt.) See American Medical Association, Alcohol and the Impaired Driver: A Manual of the Medical-Legal Aspects of Chemical Tests for Intoxication with Supplement on Breath/Alcohol Tests (1976 reprint).
The anticoagulant in the vial is designed to prevent the sample from clotting inside the vial. The preservative prevents yeast growth, which may cause the blood to ferment, thereby increasing the concentration of ethyl alcohol in the sample. Finally, the sample should be refrigerated during storage with 1% sodium fluoride. Lesser concentrations may allow microorganisms to grow, thereby inhibiting glycolysis. See Kaye, “The Collection and Handling of Blood Alcohol Specimen," 75 American Journal of Clinical Pathology 743 (1980).
Areas of concern or inquiry as to the validity of the blood sample include:
•The collection of the blood sample by the nurse, doctor or phlebotomist;
•Use of an appropriate blood collection kit;
•The transportation of the blood;
•The storage of the blood;
•The preparation of the blood for testing;
•The testing of the blood;
•The chain of command in handling the blood;
•The reporting of the blood alcohol level.