## Facts

- A serious automobile collision occurred at a rural intersection known as “Four Corners,” where S.D. Highways 34 and 63 and U.S. Highway 14 converge through a complex T/Y configuration.
- On February 13, 2004, Monny and Patricia Truman, Dee Ann Rounds, and the Rounds children traveled westbound on U.S. 14/S.D. 34 and followed U.S. 14 along a southbound curve through the intersection area.
- Richard Giago drove north on S.D. 63/U.S. 14 and continued north on S.D. 63 across a Y junction near the intersection.
- The vehicles collided, causing severe injuries and multiple deaths, including Patricia Truman and the Rounds’ unborn child.
- Plaintiffs alleged the intersection was excessively dangerous and that the Department of Transportation traffic engineer (and other DOT employees), sued in their official capacities, negligently failed to install adequate traffic-control or warning signs.
- Plaintiffs relied on SDCL 31-28-6, which directs the DOT to place and maintain traffic-control devices, signs, and markings “in conformity with standard uniform traffic control practices.”
- Defendants moved for summary judgment, asserting sovereign immunity; the circuit court granted the motion.

## Issues

1. Whether negligence claims under SDCL 31-28-6 for failure to erect highway warning signs are barred by sovereign immunity because decisions on the necessity, type, and placement of signs are discretionary rather than ministerial.

## Decision

- The Supreme Court of South Dakota affirmed summary judgment for the defendants.
- The court held sovereign immunity barred the claims because SDCL 31-28-6 does not impose a specific, mandatory (ministerial) duty to install particular warning signs at Four Corners.
- The court concluded that determining whether warning devices are needed, and their type and placement consistent with “standard uniform traffic control practices,” requires professional judgment and is a discretionary governmental function.
- The court found no express legislative waiver of sovereign immunity applicable to the plaintiffs’ theory of liability.

## Legal Principles

- Sovereign immunity protects the State and its officials from suit for discretionary acts performed within the scope of governmental authority unless immunity is expressly waived.
- A ministerial duty is “absolute, certain, and imperative” as to the time, manner, and occasion of performance, leaving no room for judgment; breach of such a duty may permit suit notwithstanding sovereign immunity.
- Statutes directing officials to act consistent with general professional standards (such as “standard uniform traffic control practices”) typically require judgment and therefore describe discretionary functions.
- Absent a binding, pre-existing directive that specifically mandates a particular sign or device at a particular location, decisions about traffic-control measures remain discretionary and are immune from negligence liability.

## Conclusion

Because SDCL 31-28-6 left the necessity for and placement of warning signs to professional engineering judgment and contained no specific command requiring particular signs at the intersection, the defendants’ conduct was discretionary and the negligence action was barred by sovereign immunity.


Truman v. Griese, 762 N.W.2d 75 (S.D. 2009)