“When Required” Means Sometimes Not Required: Traffic Stops Cannot Rest on Objectively Unreasonable Mistakes of South Dakota Turn-Signal Law (SDCL 32-26-18.1 & 32-26-22)

Precedents Cited

1) Review standards and statutory interpretation

• State v. Rosa (de novo review of suppression rulings on constitutional claims): the Court framed the appeal as a legal question reviewed without deference.
• State v. Grassrope (fact findings clearly erroneous; legal conclusions de novo): reinforced the Court’s role in independently applying Fourth Amendment and statutory standards to undisputed facts.
• State v. Biteler and State v. Bettelyoun (plain meaning; “starting point” is statutory text; read statutes as a whole): supported the Court’s conclusion that the text itself resolves the “when required” dispute.
• Ibrahim v. Dep't of Pub. Safety and People ex rel. J.W. (anti-surplusage): the Court relied on these principles to reject an interpretation that would make “when required” meaningless.
• Jans v. Dep't of Pub. Safety and Abata v. Pennington Cnty. Bd. of Comm'rs (harmonizing related statutes): used to justify reading SDCL 32-26-18.1 together with SDCL 32-26-22 so both have effect.

2) Traffic stops: reasonable suspicion, probable cause, and the “minimal” threshold

• State v. Bonacker (traffic stop requires “specific and articulable suspicion of a violation”): anchored the Court’s description of the traffic-stop exception.
• State v. Stanage (reasonable suspicion is less than probable cause) quoting Navarette v. California: supported the Court’s rejection of Hawley’s claim that probable cause was the required standard.
• State v. Hett: cited for the proposition that observation of a traffic violation provides at least reasonable suspicion; Justice Salter’s special concurrence clarified that such observation ordinarily provides probable cause as well (citing State v. Wright and State v. Akuba).
• State v. Wright: important for two reasons—(a) it discusses stops for minor traffic violations and the role of probable cause; (b) it emphasizes an officer’s subjective good faith is insufficient and officers may not rely on misunderstandings of clear statutes.
• Rodriguez v. United States (discussed in Justice Salter’s concurrence via Justice Thomas’s dissent): referenced to illustrate modern Fourth Amendment traffic-stop doctrine and to underscore that the reasonable suspicion/probable cause distinction did not decide this case.

3) Mistake-of-law doctrine and objective reasonableness

• State v. Tenold quoting Heien v. N. Carolina: the governing rule—mistakes of law (like mistakes of fact) can support a stop only if the mistake is objectively reasonable.
• United States v. Washington and United States v. Smart (cited in Justice Salter’s concurrence): reinforce that where a stop rests on a mistake of law, the constitutionality turns on objective reasonableness under either probable cause or reasonable suspicion frameworks.

4) The key substantive precedent on turn-signal requirements

• State v. Eidahl: the critical interpretive authority for SDCL 32-26-22. The Court reiterated Eidahl’s holding that SDCL 32-26-22 does not require a signal in all instances and permits turning without signaling when another vehicle will not be affected. Eidahl’s existence also made the officer’s contrary assumption harder to characterize as objectively reasonable.
• Hohm v. City of Rapid City: cited for the definitional point that “highway” includes city streets, ensuring SDCL 32-26-22 applies in municipal settings like Aberdeen.

Collectively, these precedents supplied the Court’s framework: (1) interpret the turn-signal statutes by text and harmonization, (2) evaluate the stop under Fourth Amendment traffic-stop doctrine, and (3) apply the mistake-of-law doctrine with emphasis on objective reasonableness and the presence of clarifying prior case law such as State v. Eidahl.

Legal Reasoning

1) Harmonizing SDCL 32-26-18.1 and SDCL 32-26-22

The Court’s interpretive move was straightforward: SDCL 32-26-18.1 supplies a timing requirement for signaling—“continuously during not less than the last one hundred feet traveled”—but only “when required.” SDCL 32-26-22 supplies the trigger for when signaling is required—“whenever the operation of any other vehicle may be affected”—and adds the visibility requirement directed to “the driver of such other vehicle.”

This reading gives independent meaning to “when required” and avoids surplusage. It also fits the Court’s approach to reading related statutes as a coherent whole.

2) Rejection of the circuit court’s “hypothetical possibility” analysis

The circuit court attempted to satisfy SDCL 32-26-22 by hypothesizing that a vehicle one block behind “may have been affected” if it were speeding, and by hypothesizing that residential intersections have a “high likelihood” of pedestrians or vehicles. The Supreme Court rejected this approach on two grounds:

• Record-based adjudication: suppression rulings must rest on record facts. The stipulated facts did not establish pedestrians, traffic density, or any vehicle (besides the officer) being potentially affected.
• Textual constraint: SDCL 32-26-22’s requirement that a signal be “plainly visible to the driver of such other vehicle” presupposes an actual other vehicle that may be affected—not a merely conjectural one.

3) The stop’s sole basis was a mistake of law—and it was objectively unreasonable

The Court emphasized that Officer Woehl did not stop Hawley under SDCL 32-26-22; he testified he was not familiar with it. The stop was based solely on the mistaken belief that SDCL 32-26-18.1 universally requires 100 feet of signaling before any turn.

Under State v. Tenold and Heien v. N. Carolina, a mistake of law can support a stop only if objectively reasonable. The Court found this mistake objectively unreasonable because:

• The statutory text is unambiguous (“when required”), making a universal requirement untenable under ordinary interpretive rules.
• State v. Eidahl had already interpreted SDCL 32-26-22 as not requiring signaling in all circumstances, undermining any claim that the law was uncertain.
• The officer’s admitted unfamiliarity with SDCL 32-26-22 showed an incomplete grasp of the governing law rather than a reasonable resolution of ambiguity.

With no objectively reasonable legal basis, the stop lacked reasonable suspicion (and, as Justice Salter explained, it would equally fail under probable cause).

4) Reasonable suspicion vs. probable cause did not drive the outcome

Although Hawley argued probable cause was required, the Court explained that reasonable suspicion is sufficient for a traffic stop and that an observed violation can supply that minimal justification. Justice Salter’s concurrence sharpened the point: an observed violation typically supplies probable cause, but where the “violation” depends on a mistake of law, the determinative inquiry is objective reasonableness.

Impact

• Clarification of turn-signal enforcement: Officers (and lower courts) must treat SDCL 32-26-18.1 as a timing rule that applies only when a signal is required under SDCL 32-26-22’s “other vehicle may be affected” condition.
• Constraint on “universal duty” assumptions: A blanket enforcement practice—stopping drivers for failing to signal 100 feet before every turn regardless of traffic context—invites suppression if it rests on the same mistaken universal interpretation rejected here.
• Record discipline in suppression rulings: The Court signaled that courts may not uphold stops by substituting hypothetical “could have been affected” scenarios for actual, articulable facts in the record.
• Objective reasonableness has teeth: Hawley reinforces that clear statutory text and existing judicial interpretation (notably State v. Eidahl) reduce the space for “reasonable” mistakes of law under Heien v. N. Carolina.
• DUI pipeline consequences: Because many DUI cases arise from traffic stops, Hawley may increase litigation over whether the officer identified a legally valid traffic basis grounded in the actual text of South Dakota statutes.