South Dakota’s Drunk Driving Crisis: Why We Need the Two-Hour Presumption Now
by Dan Nelson, Brookings County State’s Attorney
Most people assume that if you have a .08 blood alcohol sample in a DUI case, you will be found guilty. Unfortunately, this is not true in South Dakota where drunk driving remains a serious public safety issue. FBI data shows South Dakota is among the nation’s worst states for drunk driving, with more than 30,000 DUI arrests from January 2021 through December 2025 – giving it the highest per-capita rate in the United States. How did we get here and what should we do about it? We can remain passive and hope the problem improves on its own, or the legislature can take proactive steps to reverse this ugly trend. I, along with the State’s Attorneys Association, Sheriffs Association, Police Chiefs Association, and Attorney Generals Office, think its time for meaningful change. Reversing the drunk driving trend and making South Dakota roads safer does not require more Highway Patrol Troopers or Sheriff Deputies. The solution is to enact a law that allows common sense DUI enforcement. In this article, I explore South Dakota’s current law, explain why it falls short, and propose a more effective approach that is currently used by numerous rural, Midwestern states.
South Dakota law provides for a presumption of intoxication at .08 blood alcohol content (BAC) and requires the State to prove the driver had a .08 or more blood alcohol content (BAC) level at the time of driving or being in physical control of a vehicle. If the State proves that .08 level at the time of driving, the jury can presume that someone is intoxicated. It is a straightforward process until you insert the realities of roadside enforcement. No BAC test is ever conducted while driving; therefore, thousands of drunk drivers escape accountability by exploiting a flawed process.
In rural states, many DUI arrests happen far from facilities where blood can be drawn. First, law enforcement conducts the initial roadside DUI investigation, and then must transport the arrested person to have their blood drawn, often traveling a significant distance.This time delay rewards the drunk driver by allowing him to reduce his BAC before a nurse can withdraw a blood sample. Roadside PBT (breath test) and field sobriety tests do not test for BAC; therefore, every alcohol DUI case relies on a blood sample taken well after the driving occurred. This raises the central question in every DUI case: how can you accurately measure the person’s BAC at the time of driving when the blood sample is collected so long after?
In South Dakota, chemists engage in retrograde extrapolation – a fancy word used to determine a BAC at the time of driving when the sample was collected well after the driving occurred. Chemists testify in every DUI trial that this extrapolation is not an exact science. In fact, it depends on a host of factors, many of which law enforcement cannot collect in most DUI investigations. Common factors that impact extrapolation include knowing when the person started and stopped drinking that night, how much alcohol they consumed, and whether they had anything to eat during that time. Most drivers make misleading statements or simply refuse to answer questions about these factors. Bottom line, most DUI cases lack the evidence needed for accurate BAC extrapolation. This forces chemists to speculate, leaving judges and juries to guess a driver’s BAC at the time of the offense. For this reason, thousands of DUIs are reduced to lesser charges, resulting in less accountability for drunk drivers. Accountability is foundational to deterrence, which is why a change in the law is necessary. It’s a broken process that demands reform.
To solve this problem, our bordering states have enacted a common sense solution. Those states acknowledged that a vast majority of DUI blood samples are collected within a two hour time frame – the same two hour time frame that chemists would use the uncertain and inexact extrapolation process to attempt to determine the driver’s BAC.
The states fixed this by extending the presumption of intoxication to within two hours of driving the vehicle. Simply stated, if a driver has a BAC of .08 or greater within two hours of driving, they are presumed to have been intoxicated while driving. By keeping the .08 BAC level, but expanding the presumption window to two hours, it removes the need to perform the extrapolation process. It is a simple and straightforward approach that eliminates the ambiguity present in most DUI investigations and results in less speculation by the jury and judges
The public policy of this rule is rooted in common sense. If you have a blood alcohol result of .08 or greater within two hours of driving, you should be presumed to be intoxicated.
The laws surrounding DUIs must be fair while acknowledging the realities of roadside enforcement. Public safety and law enforcement should not be compromised or rendered ineffective because of time delays caused by location of arrest or the inexact science of extrapolation. It is time for South Dakota to embrace a new approach to DUI enforcement. If you believe we should work to reverse the ugly trend of increasing DUIs on South Dakota roads, please help us by encouraging your legislator to vote yes on HB 1120.