This may help a little more. From SC Law:
SECTION 23-31-410. Blood and urine testing.
(A) A person who uses a firearm within this State shall submit to a SLED-approved breath test to determine the alcoholic content of the blood and to a urine test to detect the presence of a controlled substance if there is probable cause to believe that the person was using a firearm while under the influence of alcohol or a controlled substance or if the person is arrested lawfully for an offense allegedly committed while he was using a firearm while under the influence of alcohol or a controlled substance. The breath or urine test must be administered at the request of a law enforcement officer who has probable cause to believe the person was using the firearm while under the influence of alcohol or a controlled substance. The administration of either test shall not preclude the administration of the other test. The refusal to submit to a breath or urine test upon the request of a law enforcement officer pursuant to this section is admissible into evidence in a criminal proceeding.
(B) If the arresting officer does not request a breath or urine test of the person arrested for an offense allegedly committed while the person was using a firearm while under the influence of alcohol or a controlled substance, the person may request the arresting officer to have a breath test made to determine the alcohol content of the person’s blood or a urine test for the purpose of determining the presence of a controlled substance. The failure of the person who requests a breath or urine test to actually be so tested shall bar the prosecution of the person for using a firearm while under the influence of alcohol or a controlled substance.
(C) The provisions of Section 56-5-2950 relating to the administration of tests for determining the weight of alcohol in an individual’s blood, additional tests at the individual’s expense, availability of test information to the individual or the individual’s attorney, and liability of medical institutions and persons administering the tests are applicable to this section.
(D) The results of a test administered pursuant to this section for the purpose of detecting the presence of a controlled substance are not admissible as evidence in a criminal prosecution for the possession of a controlled substance.
(E) Information obtained pursuant to this section must be released to a court, prosecuting attorney, defense attorney, or law enforcement officer in connection with an alleged violation of Section 23-31-400 upon request for this information.
SECTION 23-31-415. Testing following death or serious personal injury; effect of refusal; evidentiary use.
(A) If a law enforcement officer has probable cause to believe that a person used a firearm while under the influence of alcohol or a controlled substance and caused the death or serious bodily injury of an individual, the person shall submit, upon the request of the law enforcement officer, to a test of his blood for the purpose of determining its alcohol content or for the presence of a controlled substance.
(B) A criminal charge resulting from the incident precipitating the officer’s demand for testing should be tried concurrently with a charge of a violation of Section 23-31-400. If the charges are tried separately, the fact that the person refused, resisted, obstructed, or opposed testing is admissible at the trial of the criminal offense which precipitated the demand for testing.
(C) The results of any test administered pursuant to this section for the purpose of detecting the presence of a controlled substance is not admissible as evidence in a criminal prosecution for the possession of a controlled substance.
Notwithstanding another provision of law pertaining to the confidentiality of hospital records or other medical records, information obtained pursuant to this section must be released to a court, prosecuting attorney, defense attorney, or law enforcement officer in connection with an alleged violation of Section 23-31-400 upon request for such information.
SECTION 23-31-420. Presumptions.
(A) Upon the trial of a civil or criminal action or proceeding arising out of acts alleged to have been committed by a person while using a firearm while under the influence of alcohol or a controlled substance, the results of any test administered pursuant to Section 23-31-410 or 23-31-415 and this section are admissible into evidence, and the amount of alcohol in the person’s blood at the time alleged, as shown by chemical analysis of the person’s blood or breath, creates the following presumptions:
(1) If there was at that time five one-hundredths of one percent or less by weight of alcohol in the person’s blood, it must be presumed that the person was not under the influence of alcohol.
(2) If there was at that time in excess of five one-hundredths of one percent but less than eight one hundredths of one percent by weight of alcohol in the person’s blood, this fact does not give rise to any inference that the person was or was not under the influence of alcohol to the extent that his normal faculties were impaired, but this fact may be considered with other competent evidence in determining whether the person was under the influence of alcohol.
(3) If there was at that time eight one hundredths of one percent or more by weight of alcohol in the person’s blood, this fact creates an inference that the person was under the influence of alcohol.
(B) The percent by weight of alcohol in the blood must be based upon grams of alcohol per one hundred milliliters of blood. The provisions of this section must not be construed as limiting the introduction of any other competent evidence bearing upon the question of whether the person was under the influence of alcohol.
