What Do Prosecutors Need to Prove in a South Carolina DUI Case?

by | Apr 1, 2018 | DUI Lawyer

When you get arrested for driving under the influence (DUI) in South Carolina, you are innocent until proven guilty. You are entitled to this “presumption of innocence,” and it is the prosecutor’s job to prove that you deserve to be convicted.

While the burden of proof rests on the prosecution, prosecutors in South Carolina can—and frequently do—secure DUI convictions. Here, Rock Hill defense attorney Michael Brown explains what it takes for prosecutors to prove a DUI case in South Carolina.

The Prosecution’s Burden of Proof in a South Carolina DUI Case

Driving under the influence is a criminal offense in South Carolina. This means that in DUI cases, prosecutors must prove the defendant’s guilt “beyond a reasonable doubt.”

“Beyond a reasonable doubt” is the highest burden of proof in the U.S. justice system. But, despite the fundamental importance of the prosecution’s burden of proof in criminal cases, it is not well-defined. For example, in South Carolina, judges typically use one of two definitions when providing instructions to the jury. In most cases, the judge will instruct the jury that either:

  • Reasonable doubt is the kind of doubt that would cause a reasonable person to hesitate to convict; or,
  • Reasonable doubt is the kind of doubt that prevents you from being firmly convinced of the defendant’s guilt.

In either case, the “beyond a reasonable doubt” standard sets a high bar. Even so, it is a bar that prosecutors can overcome—and it is a bar that they do overcome in many cases. As a result, DUI defendants need to take their cases very seriously, and this starts with hiring an experienced defense lawyer as soon after their arrest as possible.

The Three “Elements” of a DUI Charge in South Carolina

Another important aspect of prosecutors’ burden of proof is that they must meet this burden with respect to each “element” of the defendant’s charge. Under South Carolina’s DUI statute (Section 56-5-2930 ), there are three “elements” that prosecutors need to prove:

  • The defendant was driving a motor vehicle;
  • The defendant was under the influence of alcohol; and,
  • The defendant’s ability to drive was “materially and appreciably impaired.”

1. Driving a Motor Vehicle

South Carolina’s DUI law only prohibits drunk driving behind the wheel of a “motor vehicle.” The law defines a “motor vehicle” as: “[A] passenger car, truck, van, or recreational vehicle required to be equipped with safety belts by Federal Motor Vehicle Safety Standard No. 208 (49 CFR 571.208), manufactured after July, 1966.” If you got pulled over but you weren’t behind the wheel of a “motor vehicle,” then you aren’t guilty of DUI.

2. Under the Influence of Alcohol

To secure a DUI conviction in South Carolina, prosecutors must be able to prove that the defendant was “under the influence” of alcohol or another drug. While the law does not specifically define what it means for a person to be under the influence, it provides that a blood alcohol concentration (BAC) of 0.06 or 0.07 percent can be considered evidence of guilt, and that a BAC of 0.08 percent or above creates an “inference” that the defendant was under the influence behind the wheel.

This means that a high BAC is not conclusive evidence of being under the influence. However, it also means that a high BAC is not the only evidence prosecutors can use to establish guilt in a DUI case. So, even if you refused the breath test (or your BAC reading is invalid or unreliable), prosecutors may still be able to prove that you were under the influence through other means.

3. “Materially and Appreciably Impaired”

In addition to proving that you were under the influence, prosecutors must also be able to prove that your ability to drive was “materially and appreciably impaired.” What does this mean? Once again, the statute is not entirely clear. While prosecutors will try to use this lack of clarity to their advantage, an experienced criminal defense lawyer can also use it to raise questions about the sufficiency of the prosecution’s evidence of guilt.


When talking about what prosecutors need to prove in a South Carolina DUI case, it is also important to address the distinction between DUI and DUAC.

In South Carolina, DUAC is short for “driving with an unlawful alcohol concentration.” If you took the breath test and blew above the legal limit, there is a good chance that you are being charged with DUAC. In a DUAC case, the “elements” that prosecutors need to prove are different. To secure a conviction, prosecutors only need to prove that:

  • The defendant was driving a motor vehicle; and,
  • The defendant’s BAC was 0.08 percent or above.

In a DUAC case, it doesn’t matter if you were under the influence, and it doesn’t matter if your driving abilities were “materially and appreciably impaired.” If prosecutors can prove that you were driving a motor vehicle and your BAC was over the legal limit, this is enough to satisfy their burden of proof.

What Evidence Can Prosecutors Use in a DUI (or DUAC) Case?

When pursuing DUI charges, prosecutors can use a variety of forms of evidence to prove influence and impairment. Some examples include:

  • The arresting officer’s observations before your traffic stop
  • The arresting officer’s observations during your traffic stop
  • Dash camera footage from the police car
  • Your field sobriety test (FST) results
  • Your breathalyzer test result
  • Statements you made during or after your arrest

What about a DUAC case? Remember, in these cases, all prosecutors need to prove is that your BAC was 0.08 percent or above. As a result, if your breathalyzer test result is admissible in court, this could be all prosecutors need to convict you.

Discuss Your DUI (or DUAC) Case with an Experienced Defense Attorney in Rock Hill, SC

While prosecutors have a variety of ways to prove defendants’ guilt in drunk driving cases, there are also several possible defenses to DUI (and DUAC) charges in South Carolina. If you would like to know what defenses you can use to fight your case, call 803-328-8822 or contact us online for a free consultation.

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