1005 N. Marion St.
Tampa, FL 33602

Hospital or Medial Blood Test in DUI Prosecutions

Depending on the allegations in the information filed in the case, a hospital blood test may be relevant to establishing the DUI charge as alleged in the charging document. Your attorney will fight to have the hospital blood test results excluded from evidence at trial.

If the prosecutor attempts to obtain a person’s medical records to obtain evidence about their BAC from blood was drawn for medical purposes, it is important to understand the difference between a whole blood test and a blood plasma test.

The hospital will usually perform a blood plasma test instead of testing whole blood. The plasma blood test is performed on the liquid portion of a drawn blood sample after the solid cellular components have been removed. For a legal blood test, the test is performed on whole blood or blood that has not been broken down into solid and liquid components.

The distinction between the hospital blood and the legal blood becomes important when considering the reported BAC results because a plasma test will produce a result that is more than 10–15% higher than a whole blood test drawn at the same time. Expert testimony is usually required to explain the how the plasma BAC would equate to a determination of whole blood BAC.

Contact an experienced criminal defense attorney at Sammis Law Firm in Tampa, FL. Call us to find out more about defenses to blood testing in DUI cases. Call 813-250-0500.

Are Hospital Blood Tests Admissible in DUI Cases in Florida?

In 2000, the supreme court answered a certified question from the Fourth District which established that records of hospital blood tests can be admitted in DUI cases. See Baber v. State, 775 So. 2d 258, 382 (Fla. 2000), cert. denied, 532 U.S. 1022 (2001).

After the United States Supreme Court's decision in Crawford v. Washington, 541 U.S. 36 (2004), the predicate steps necessary to introduce such evidence are far more complicated in order to satisfy the requirements of confrontation, see Johnson v. State, 929 So. 2d 4, 7-8 (Fla. 2d DCA 2005), but it remains clear that such medical tests can be relevant to establish a DUI.

Given the differences between legal blood tests and medical or serum blood tests, at a minimum, a hospital blood test may need to be supported by additional expert evidence to be relevant and admissible in a case under a blood-alcohol theory. But in a case under an impairment theory, medical or serum blood tests are more likely to be admissible with a lesser degree of expert testimony. See J.J. Paul, III, DWI: Blood, Tests & Fears: A Crash Course in Blood Alcohol Samples, 25 Champion 39 (June 2001); Carol A. Roehrenbeck & Raymond W. Russell, Blood is Thicker than Water: What You Need to Know to Challenge a Serum Blood Alcohol Result, 8 Crim. Just. 14 (Fall 1993).

DUI can be established under several alternative theories. In cases involving alcohol intoxication, a prima facie case can be established by proof that a person operating or in actual physical control of a vehicle is “under the influence of alcohol . . . to the extent that [his or her] normal faculties are impaired,” § 316.193(1)(a), Fla. Stat. (2009), the person has “a blood-alcohol level of 0.08 or more grams of alcohol per 100 milliliters of blood,” § 316.193(1)(b), or the person has “a breath-alcohol level of 0.08 or more grams of alcohol per 210 liters of breath.” § 316.193(1)(c).

How to Convert Serum and Plasma Results to Whole Blood

Since it represents the water portion of whole blood, serum or plasma will have a higher AC than the whole blood from which it is derived.This means that serum and plasma alcohol results must be reduced to obtain a whole blood equivalent.The average ratio of serum and plasma AC to whole blood AC is approximately 1.14:1 (range 1.04:1 – 1.26:1).

To convert a serum alcohol concentration to a whole blood equivalent:

Step 1.

If necessary, convert the units to g/100 mL.

mg/dL = mg/100 mL

mg/100 mL = g/100 mL



120 mg/dL = 0.120 g/100 mL

Step 2.

Convert serum alcohol concentration (SAC) to an equivalent whole blood concentration (your witness may use a different average ratio than 1.14:1):Whole Blood AC = SAC /1.14.

0.120 = 0.105 g/100 mL = average whole blood equivalent



Conversion Between Alcohol Concentrations in Whole Blood, Plasma Blood and Serum Blood

Enzymatic assay testing is used in hospitals for determining the alcohol concetration in plasma or serum.

The plasma is gathered when whole blood is centrifuged or spun and the red blood cells, white blood cells, and platelets are removed.

The serum is gathered in the same way except that coagulation proteins are also removed.

The result of the plasma or serum for alcohol concentration will retrun a result that is 16-25% higher than the alcohol concentration in whole blood. Different conversion numbers are used by different experts. The most common range used is .13 to .20. In some cases, a technical supervisor will use .16.

For example, if a .10 serum/plasma alcohol concentration is converted to a whole blood alcohol concentration, the following calculations will result:

  • .10 / 1.25 = .080
  • .10 / 1.20 = .083
  • .10 / 1.18 = .084
  • .10 / 1.16 = .086

DUI Defense Attorneys for the Blood Test in Tampa, Florida

If your driving under the influence (DUI) cases involves blood testing, then contact an experienced DUI defense lawyer in Tampa, Florida. The attorneys at Sammis Law Firm in Tampa, FL, are experenced in represent clients throughout the Tampa Bay area. Call us for a free consultation to discuss your case.

Find out more about the charges pending against you, the method used to for the DUI blood test and defenses that might apply to your case.

Call 813-250-0500 to discuss your case.

This article was last updated on Thursday, March 2, 2017.