## Facts

- Judith Kay Graber was seriously injured in a 1996 collision at the T-intersection of State Street and Oralabor Road in Ankeny, Iowa, which was controlled by traffic signals.
- Graber entered the intersection on a green light to make a left turn.
- Kristie Allen, traveling eastbound, entered the intersection against a red light and struck Graber’s vehicle broadside.
- Allen testified the signal changed from green to yellow to red too quickly to allow her to stop safely.
- Graber sued the City of Ankeny, alleging negligent timing of the traffic signal phases and failure to comply with the Manual on Uniform Traffic Control Devices (MUTCD), which Iowa had adopted as the governing standard for traffic-control devices.
- After a prior defense verdict and a remand for a new trial based on evidentiary error, the City asserted immunity under Iowa Code § 670.4(3) and obtained summary judgment on the ground that signal-timing decisions were discretionary functions.

## Issues

1. Whether the City’s timing of the traffic-signal sequence involved a “discretionary function or duty” under Iowa Code § 670.4(3).
2. Whether applying (or deviating from) MUTCD-governed signal-timing standards constitutes policy-based discretion or operational/technical implementation outside discretionary-function immunity.

## Decision

- The Iowa Supreme Court reversed the summary judgment for the City and remanded for further proceedings.
- The court held the City’s signal-timing conduct was not a discretionary decision grounded in legitimate public policy considerations within Iowa Code § 670.4(3).
- The court concluded the challenged conduct was primarily technical implementation of an adopted mandatory standard, not the type of policy choice the immunity provision protects.

## Legal Principles

- Iowa Code § 670.4(3) immunizes municipalities only for discretionary functions that are based on public policy considerations, even if the discretion is abused.
- Discretionary-function analysis uses a two-step test:
  - The conduct must involve judgment or choice; and
  - The judgment must be the type the immunity is designed to protect—i.e., grounded in social, economic, or political policy.
- When the government has adopted specific, mandatory standards to guide conduct, negligent implementation or deviation from those standards is generally operational conduct, not protected policy discretion.
- Professional or engineering judgments applying technical standards, without identification of competing policy choices actually being weighed, do not satisfy the policy-based prong required for discretionary-function immunity.
- Where state law makes the MUTCD the controlling standard for traffic-control devices, compliance-related timing decisions are constrained by that framework and are less likely to qualify as policy-level discretion.

## Conclusion

The court held that a municipality’s traffic-signal timing decisions, when made within and constrained by mandatory MUTCD standards and reflecting technical implementation rather than policy balancing, are not protected by discretionary-function immunity, so the negligence claim could proceed on remand.


Graber v. City of Ankeny, 656 N.W.2d 157 (Iowa 2003)