Robert A. Lamar, a laborer for Corrigan Company, was injured when a ditch caved in on him while he was working on a sewer system for the city of St. Louis. He brought suit against two private contractors, the local sewer board, and the city of St. Louis alleging that each of the parties failed to reinforce the sides of the ditch and failed to warn him about the condition of the ditch. The claims against the sewer board and the private contractors were dismissed; this left just the city as a defendant. Lamar amended his petition to include the allegation that the city had maintained a barricade, manned by personnel, to keep traffic out of the lane adjacent to the ditch in which he worked, but that the city had negligently removed both the barricade and the personnel without warning him. After the protection had been removed, traffic vibrations caused the ditch to cave in and left Lamar permanently injured.

The city asked for, and received, a summary judgment in the Circuit Court on the grounds that its actions were immune under the governmental function of regulating traffic. The Court of Appeals agreed that regulating traffic is an immune governmental function, but determined that constructing sewers was a proprietary function and not immune from tort liability.

For the higher court, then, the city's alleged negligence had to be judged not in light of regulating traffic around a work zone, but rather as a proprietary function of creating and maintaining a safe work zone. The court found that when engaged in constructing a sewer, a city is involved in a proprietary function, and therefore has responsibility for the protection of the public and the workers. In response to Lamar's interrogatories, the city admitted that its Department of Public Utilities, Water Division, "had responsibility for the work being performed at the excavation," and that the city "had specifications for the project."

The Court of Appeals reversed the summary judgment, finding that the city had been granted such judgment on the wrong grounds. Protecting laborers in a work zone constituted more than "regulating traffic." Lamar was given the right to a new trial.