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ADVANCE SHEET HEADNOTE

January 14, 2019

2019 CO 2

No. 18SA180, People v. Burnett—Searches and Seizures—Reasonable Suspicion—

Mistake of Law.

In this interlocutory appeal, the supreme court considers whether a Colorado State 

Patrol trooper made a reasonable mistake of law when the trooper stopped a car for 

making what he believed to be an illegal lane change after witnessing the driver flash her

turn signal twice over a distance of less than 200 feet and then change lanes. The supreme 

court holds that the trooper’s erroneous interpretation of the governing statute, section 

42-4-903, C.R.S. (2018), did not constitute an objectively reasonable mistake of law. It is 

plain from the text of the statute that a driver is not required to signal continuously for 

any set distance before changing lanes on a highway; the statute only requires that a 

driver use a signal before changing lanes. Thus, because this was not a reasonable 

mistake of law, the trooper did not have reasonable suspicion to justify the investigatory 

stop. The supreme court therefore affirms the trial court’s suppression order. 
The Supreme Court of the State of Colorado

2 East 14th Avenue • Denver, Colorado 80203

2019 CO 2

Supreme Court Case No. 2018SA180

Interlocutory Appeal from the District Court

El Paso County District Court Case No. 18CR950

Honorable Gregory R. Werner, Judge

Honorable Gilbert A. Martinez, Senior Judge

______________________________________________________________________________

Plaintiff-Appellant:

The People of the State of Colorado,

v.

Defendant-Appellee:

Devon Paul Garrett Burnett.

______________________________________________________________________________

Order Affirmed

en banc

January 14, 2019

______________________________________________________________________________

Attorneys for Plaintiff-Appellant:

Daniel H. May, District Attorney, Fourth Judicial District

Andrew Lower, Deputy District Attorney

Doyle Baker, Senior Deputy District Attorney

Colorado Springs, Colorado

Attorneys for Defendant-Appellee:

Megan A. Ring, Public Defender

Max E. Shapiro, Deputy Public Defender

Colorado Springs, Colorado

JUSTICE HOOD delivered the Opinion of the Court.

JUSTICE BOATRIGHT dissents, and CHIEF JUSTICE COATS joins in the dissent.
2

¶1 While driving down a highway, a Colorado State Patrol (CSP) trooper observed 

another driver flash her turn signal twice over a distance of less than 200 feet and then 

change lanes. Apparently believing he’d just witnessed an illegal lane change, the trooper

stopped the car in which there was a passenger—the defendant, Devon Burnett. 

¶2 A subsequent search of the car revealed a handgun, drug paraphernalia, and 

suspected methamphetamine. As a result, Burnett was charged with multiple offenses, 

including possession with intent to manufacture or distribute a controlled substance and 

possession of a weapon by a previous offender. 

¶3 Burnett filed a motion to suppress the evidence found during the search that 

flowed from the stop for the allegedly illegal lane change. He argued that the statute 

governing turning movements and required signals, section 42-4-903(2), C.R.S. (2018),

doesn’t require a person to signal for a minimum distance before changing lanes; 

therefore, the trooper did not have reasonable suspicion to stop the car. The trial court 

agreed and suppressed the fruits of the search. 

¶4 The People filed this interlocutory appeal, contending in part that the trooper at 

worst made an objectively reasonable mistake of law when he concluded that changing

lanes on the highway without signaling for 200 feet violated section 42-4-903(2). 

Consequently, the People argue that the trooper had reasonable suspicion to stop the car. 

¶5 We conclude that the trooper’s construction of section 42-4-903(2) was objectively 

unreasonable. The plain language of the statute clearly distinguishes between turns and 

lane changes, and the statute does not require a driver to signal continuously for any set 
3

distance before changing lanes on a highway—it only requires that a driver use a signal 

before changing lanes. Therefore, we affirm the trial court’s suppression order.

I. Facts and Procedural History1

¶6 Burnett was a passenger in a black sedan traveling along Highway 21 in El Paso 

County. Trooper Stephen Wall watched as the driver engaged the sedan’s turn signal, 

allowed it to flash twice for less than 200 feet, and then changed lanes. Trooper Wall 

stopped the sedan. 

¶7 As the sedan pulled over, Trooper Wall noticed the passenger moving around in 

a manner that suggested he could be “attempt[ing] to conceal contraband or produce a 

weapon.” Concerned for his safety, Trooper Wall radioed for cover. When Trooper Wall 

approached the car, he noticed that Burnett looked unusually nervous. This seemed 

strange to Trooper Wall, considering Burnett was only the passenger and not the subject 

of the stop. In addition to asking for the driver’s identification, Trooper Wall asked 

Burnett to show the trooper his identification. Burnett complied. 

¶8 After dispatch advised Trooper Wall that Burnett was subject to a restraining order 

that prohibited Burnett from possessing weapons, another trooper observed a handgun 

magazine on the passenger side of the car. Law enforcement personnel then searched the 

entire passenger compartment. The troopers found a handgun underneath Burnett’s seat,

along with a substance believed to be methamphetamine, drug paraphernalia, baggies, 

 

1 These facts are drawn from undisputed testimony and the trial court’s findings made at 

the suppression hearing.
4

and a scale. CSP arrested Burnett, who was later charged with multiple offenses, 

including possession with intent to manufacture or distribute a controlled substance and

possession of a weapon by a previous offender.

¶9 Burnett moved to suppress all evidence resulting from the stop, claiming Trooper 

Wall had no reasonable suspicion to believe a traffic violation had occurred under section 

42-4-903(2). The trial court granted the motion to suppress, concluding that section 

42-4-903(2) does not require a car to signal continuously for 200 feet before changing lanes 

on a highway—“that only applies to turning right or left.” 

¶10 The People filed a motion to reconsider the suppression order, arguing that the 

trooper made a reasonable mistake of law because section 42-4-903(2) can be read as

applying to lane changes. They contended that under Heien v. North Carolina, 135 S. Ct. 

530 (2014), this objectively reasonable mistake of law provided reasonable suspicion for 

the traffic stop. The trial court denied the motion to reconsider, without explicitly 

addressing the reasonable mistake of law argument under Heien.

2 

¶11 The People filed this interlocutory appeal.

 

2 The People raised the Heien argument for the first time in their motion to reconsider. 

Burnett responded to the argument, first urging the court to apply a plain error standard 

to review the Heien argument and, alternatively, arguing that if the court reached the 

merits of the People’s argument, Trooper Wall’s mistake was not reasonable. Although 

the trial court did not explicitly address Heien when denying the motion to reconsider, it

did address the merits of the People’s argument. Accordingly, we too reach the merits of 

the underlying motion to suppress.
5

II. Analysis

¶12 We first review relevant Fourth Amendment principles, including precedent from 

the U.S. Supreme Court stating that an objectively reasonable mistake of law can support 

a finding that there was reasonable suspicion to justify an investigatory stop. We then 

address section 42-4-903 and determine that its plain language only requires that a driver 

signal before changing lanes—it does not require a driver to signal continuously for any 

set distance before changing lanes. Because the text of the statute is clear, we conclude 

that the trooper’s construction of section 42-4-903 was not objectively reasonable. 

A. Standard of Review

¶13 A trial court’s order suppressing evidence presents a mixed question of law and 

fact. People v. Chavez-Barragan, 2016 CO 16, ¶ 9, 365 P.3d 981, 983. “We accept the trial 

court’s findings of historic fact if those findings are supported by competent evidence, 

but we assess the legal significance of the facts de novo.” Id. We also review “[r]elated 

issues of statutory construction . . . de novo.” Id.

B. The Fourth Amendment and Mistakes of Law

¶14 The Fourth Amendment to the U.S. Constitution protects individuals against 

unreasonable searches and seizures.3 U.S. Const. amend. IV. “A traffic stop for a 

 

3 Article II, Section 7 of the Colorado Constitution provides similar protections. Burnett 

encourages us to reject the reasonable-mistake-of-law doctrine by holding that Article II, 

Section 7 affords greater protection than the Fourth Amendment in this area. But, Burnett 

made no argument below clearly invoking the Colorado Constitution. And the trial court 

did not explicitly ground its suppression ruling on state constitutional law. Accordingly, 

“[i]n the absence of a clear statement that a suppression ruling is grounded on state as 
6

suspected violation of law is a ‘seizure’ of the occupants of the vehicle and therefore must 

be conducted in accordance with the Fourth Amendment.” Heien, 135 S. Ct. at 536. As 

relevant here, a brief, investigatory traffic stop is constitutional “when the officer has a 

reasonable, articulable suspicion that criminal activity ‘has occurred, is taking place, or is 

about to take place.’” Chavez-Barragan, ¶ 10, 365 P.3d at 983 (quoting People v. Ingram, 984 

P.2d 597, 603 (Colo. 1999)). An officer may thus stop a vehicle if the officer has a 

reasonable suspicion that the driver has committed a traffic violation. 

¶15 Reasonable suspicion may exist even if an officer is mistaken about a critical fact

or about the proper interpretation of a statute. However, “[t]he Fourth Amendment 

tolerates only reasonable mistakes, and those mistakes—whether of fact or of law—must 

be objectively reasonable.” Heien, 135 S. Ct. at 539.

¶16 In Heien, the Supreme Court held that an officer’s mistaken interpretation of a 

traffic law was reasonable and, thus, could still justify a stop under the Fourth 

Amendment. Id. at 534. At issue was a North Carolina statute that required drivers to 

have at least one working brake light. Id. at 535. The officer pulled a vehicle over for 

failing to have two working brake lights because he incorrectly believed that was what 

the statute required. Id. at 534. Because the language of the statute was unclear and had 

not been previously interpreted by North Carolina’s appellate courts, the U.S. Supreme 

 

opposed to federal constitutional law, we will presume that a court relied on federal law 

in reaching its decision.” People v. McKinstrey, 852 P.2d 467, 469 (Colo. 1993). 
7

Court determined that the officer’s mistaken interpretation was reasonable and could 

provide reasonable suspicion to justify the stop under the Fourth Amendment. Id. at 540.

In reaching this conclusion, the Court noted “[t]o be reasonable is not to be perfect, and 

so the Fourth Amendment allows for some mistakes on the part of government officials, 

giving them ‘fair leeway for enforcing the law in the community’s protection.’” Id. at 536 

(quoting Brinegar v. United States, 338 U.S. 160, 176 (1949)); see also Casillas v. People, 2018 

CO 78M, ¶¶ 44–45, 427 P.3d 804, 815 (Samour, J., dissenting) (discussing the rationale 

behind the Heien majority’s holding). Heien thus held that a mistaken interpretation of 

the law can still support a finding of reasonable suspicion if the mistake is objectively

reasonable. Heien, 135 S. Ct. at 539. As a corollary of this holding, courts should not 

consider the “subjective understanding of the particular officer involved.”4 Id. 

 

4 In concurrence, Justice Kagan embraced the majority’s framework and elaborated that

an officer’s ignorance of the law or lack of training are irrelevant, as is “an officer’s 

reliance on ‘an incorrect memo or training program from the police department.’” Id. at 

541 (Kagan, J., concurring) (quoting North Carolina v. Heien, 737 S.E.2d 351, 360 (N.C. 2012) 

(Hudson, J., dissenting)). The law at issue must also be “‘so doubtful in construction’ that 

a reasonable judge could agree with the officer’s view.” Id. (quoting The Friendship, 9 F. 

Cas. 825, 826 (C.C.D. Mass. 1812) (No. 5,125)). So, as Justice Kagan explained: “If the 

statute is genuinely ambiguous, such that overturning the officer’s judgment requires 

hard interpretive work, then the officer has made a reasonable mistake. But if not, not.” 

Id.

Perhaps in an effort to make the Heien majority’s general pronouncements more 

workable, some courts have looked to Justice Kagan’s concurrence in Heien for guidance. 

See, e.g., State v. Sutherland, 176 A.3d 775, 782–83 (N.J. 2018) (describing Justice Kagan’s 

concurrence as containing “several important caveats” and collecting cases that “either 

followed or acknowledged [her] narrow interpretation of an objectively reasonable 

mistake of law”); State v. Hurley, 117 A.3d 433, 441 (Vt. 2015) (discussing how “Justice 

Kagan emphasized that the bar is high” when determining whether a mistake is 
8

¶17 With these Fourth Amendment principles in mind, we now examine what section 

42-4-903 requires. 

C. Section 42-4-903

¶18 Trooper Wall stopped the car in which Burnett was a passenger, on the belief that 

a failure to signal continuously for 200 feet before changing lanes on Highway 21 

constituted a violation of section 42-4-903(2). 

¶19 The relevant provisions of section 42-4-903 require a driver to signal continuously 

for 200 feet when intending to turn on any highway where the posted speed limit is more 

than forty miles per hour, but it also distinguishes between turns and lane changes. In 

relevant part, the statute provides: 

(2) A signal of intention to turn right or left shall be given continuously 

during not less than the last one hundred feet traveled by the vehicle before 

turning in urban or metropolitan areas and shall be given continuously for 

at least two hundred feet on all four-lane highways and other highways 

where the prima facie or posted speed limit is more than forty miles per 

hour. . . .

. . . . 

(4) The signals provided for in section 42-4-608(2) shall be used to indicate 

an intention to turn, change lanes, or start from a parked position and shall 

not be flashed on one side only on a parked or disabled vehicle or flashed 

 

reasonable); State v. Houghton, 868 N.W.2d 143, 158 (Wis. 2015) (citing Justice Kagan’s 

explanation of an objectively reasonable mistake of law). 

We need not decide whether to join those courts that have relied upon Justice Kagan’s 

concurrence in order to effectuate the majority’s holding in Heien. While her thoughts 

might prove instructive in another case, they are not necessary for us to resolve the case 

before us today. 
9

as a courtesy or “do pass” signal to operators of other vehicles approaching 

from the rear.

§ 42-4-903.

5

¶20 We employ common tools of statutory interpretation to aid in our understanding

of this statute. “In construing a statute, we seek to give effect to the General Assembly’s 

intent by according words and phrases their plain and ordinary meanings.” People v. 

Stellabotte, 2018 CO 66, ¶ 32, 421 P.3d 174, 180 (quoting State Farm Mut. Auto. Ins. Co. v. 

Fisher, 2018 CO 39, ¶ 12, 418 P.3d 501, 504). We therefore look to the text of the statute 

first and, if it is clear, “we apply the plain and ordinary meaning of the provision.” Perfect 

Place, LLC v. Semler, 2018 CO 74, ¶ 40, 426 P.3d 325, 332. A statute must also be considered 

“as a whole, construing each provision consistently and in harmony with the overall 

statutory design.” Id. (quoting Whitaker v. People, 48 P.3d 555, 558 (Colo. 2002)). We may 

not construe a statute in a manner that would render any words or phrases superfluous. 

People v. Rediger, 2018 CO 32, ¶ 22, 416 P.3d 893, 899. 

¶21 The plain language of the statute treats “turning right or left” differently from 

“changing lanes.” Subsection (2) outlines the requirements for a driver turning right or 

left, while subsection (4) delineates when a turn signal must be used to, among other 

things, turn or change lanes. By referring to both lane changes and turns in subsection 

(4), the legislature made clear that the term “turn” in subsection (2) does not encompass 

 

5 Section 42-4-608(2), C.R.S. (2018), requires that motor vehicles that exceed specified 

measurements “be equipped with . . . signal lamps” and that those signal lamps be used 

on highways to give required signals. 
10

the act of changing lanes. “[T]he use of different terms signals an intent on the part of the 

General Assembly to afford those terms different meanings.” Id. (quoting Robinson v. 

Colo. State Lottery Div., 179 P.3d 998, 1010 (Colo. 2008)). To interpret the statute otherwise 

would render language in subsection (4) superfluous—if a “turn” includes a “lane 

change,” then there would have been no need to state specifically in subsection (4) that a 

signal must be used when changing lanes. Accordingly, the provision that Trooper Wall 

believed the driver of the black sedan violated, subsection (2), does not apply to lane 

changes. Because subsection (2) does not apply to lane changes, and because there was 

no violation of subsection (4) since the driver signaled twice before changing lanes, 

Trooper Wall did not witness a traffic violation before stopping the car in which Burnett 

was a passenger. 

¶22 So, it was a mistake of law for Trooper Wall to interpret section 42-4-903 as he did. 

We now consider whether this mistake of law was nevertheless objectively reasonable.

D. The Mistake of Law Was Objectively Unreasonable

¶23 The People argue that section 42-4-903(2) can reasonably be construed as Trooper 

Wall apparently construed it. We disagree. Because section 42-4-903(2) is unambiguous, 

we conclude that Trooper Wall’s mistake of law was not objectively reasonable. 

¶24 The statute requires vehicles to signal continuously for at least 200 feet before 

turning right or left on a highway. There is no ambiguity as to whether a turn includes a 

lane change because subsection (4) specifically lists lane changes as distinct from turns. 

Thus, there is no need to consider whether a lane change is a type of turning movement 

encompassed in the definition of “turn” as the People suggest. Regardless of whether 
11

“turn” is defined broadly enough to include lane changes, the statutory scheme treats 

turns and lane changes differently. Consequently, Trooper Wall’s interpretation was not 

objectively reasonable under the plain language of the statute. 

¶25 Though this is the first time section 42-4-903 has been interpreted by one of our

appellate courts, the lack of such precedent does not transform Trooper Wall’s 

interpretation into an objectively reasonable reading of the provision. While it is more 

likely that a mistake of law may be reasonable if there is no precedent contrary to an 

officer’s reading of a statute, lack of precedent alone cannot rehabilitate a statutory

interpretation that is unwarranted by the plain language and structure of the statute. See

United States v. Stanbridge, 813 F.3d 1032, 1037 (7th Cir. 2016) (“Heien does not support the 

proposition that a police officer acts in an objectively reasonable manner by 

misinterpreting an unambiguous statute.”). 

¶26 The People offer United States v. Rubio-Sepulveda, 237 F. Supp. 3d 1116 (D. Colo. 

2017), appeal docketed, No. 18-1055 (10th Cir. Feb. 13, 2018), as support for their argument 

that “the scope of subsection (2) remains unsettled until resolved by the appellate courts 

of this state.” In Rubio-Sepulveda, law enforcement stopped the defendant’s car for failing 

to signal continuously for a set distance before changing lanes. Id. at 1122. Though the 

federal district court ultimately deemed the stop valid for another reason, in a footnote 

the court discusses reasonable mistake of law. Concluding that the officer erred because 

section 42-4-903 “does not plainly contemplate a failure to signal for [a required distance]

before changing lanes,” id. at 1122 n.4, the federal district court found this mistake 

reasonable because there was no precedent interpreting the statute, and the Department 
12

of Revenue’s driver handbook contained the same incorrect interpretation. Id. But this 

footnoted analysis misses the mark—as previously noted, an appellate court need not

explicitly define the parameters of a clear and unambiguous statute. And here, that is 

what we have. Thus, the People’s reliance on Rubio-Sepulveda is misplaced.

¶27 For two reasons, we are also unpersuaded by the presence of an erroneous 

interpretation of section 42-4-903(2) in the Department of Revenue’s driver handbook

stating that a turn signal is required for at least 200 feet prior to changing lanes. First, 

there is no evidence in the record that Trooper Wall reviewed or relied on the 

Department’s interpretation. And even if Trooper Wall had read the handbook, it would 

be irrelevant to our analysis because it would relate to the trooper’s subjective 

understanding of the section and therefore couldn’t justify the seizure. Heien, 135 S. Ct. 

at 539. Second, the handbook expressly states that “[i]t is not a book of laws and should 

not be used as a basis for any legal claims or actions. It is a book of information only and 

does not supersede Colorado Revised Statutes.” Div. of Motor Vehicles, Colo. Dep’t of 

Revenue, DR-2337, Colorado Driver Handbook 4 (2017). The handbook also refers readers 

back to Title 42, which does not require vehicles to signal continuously for either 100 or 

200 feet before simply making a lane change. 
13

¶28 Because Trooper Wall’s interpretation of section 42-4-903 runs counter to the plain 

text of the statute, we conclude that his interpretation was not objectively reasonable and 

cannot support a finding of reasonable suspicion to justify the traffic stop at issue here.

6

III. Conclusion

¶29 We conclude that Trooper Wall’s construction of section 42-4-903(2) was not an 

objectively reasonable mistake of law. It is plain from the text of the statute that a driver

is not required to signal continuously for any set distance before changing lanes on a 

highway. The statute only requires that a driver use a signal before changing lanes. 

Therefore, we affirm the trial court’s suppression order.

JUSTICE BOATRIGHT dissents, and CHIEF JUSTICE COATS joins in the dissent.

 

6 Because the parties have not addressed what remedy should follow if the stop was 

invalid, we are not confronted with the question of whether the proper remedy was

exclusion of evidence. In cases such as this, there are potentially two issues: (1) whether 

law enforcement violated the Fourth Amendment; and, (2) if so, whether the remedy 

should be exclusion. Heien, 135 S. Ct. at 539; Casillas, ¶¶ 29–30, 427 P.3d at 812 (majority 

opinion). In the notice of interlocutory appeal, the People framed the issue as follows: 

“Did the district court err in concluding that [the] trooper who stopped the car in which 

[the] defendant was riding made the stop without reasonable suspicion that a traffic 

infraction had occurred?” And in their briefs, both parties limited their arguments to 

whether there was a Fourth Amendment violation. Neither party briefed application of 

the exclusionary rule. Because “we rely on the parties to frame the issues for decision 

and assign to courts the role of neutral arbiter of matters the parties present,” Greenlaw v. 

United States, 554 U.S. 237, 243 (2008), we decline to address whether the exclusionary 

rule should apply in this instance. In the absence of any argument to the contrary, 

exclusion remains the remedy here. 
1

JUSTICE BOATRIGHT, dissenting.

¶30 The majority finds Trooper Wall’s interpretation of section 42-4-903(2), C.R.S. 

(2018), objectively unreasonable. I disagree for three reasons. First, Trooper Wall’s 

interpretation of the statute was arguably correct. Second, even if his interpretation was 

incorrect, it was objectively reasonable. Finally, even if Trooper Wall was incorrect and 

objectively unreasonable, his conduct does not warrant application of the exclusionary 

rule. Therefore, I respectfully dissent.

¶31 While the majority correctly recites the facts, it is important to note the immediate 

circumstances of the traffic stop. Trooper Wall was driving on a highway with a speed

limit of fifty-five miles per hour when he saw a car give two quick blinks of its turn signal 

and change lanes. At such a speed, that is not enough notice to change lanes safely. I 

must note that over 250,000 accidents are caused by lane-change errors each year in the 

United States, meaning that one lane-change accident occurs every two minutes. See Nat’l 

Highway Traffic & Safety Admin., U.S. Dep’t of Transp., DOT HS 809 571, Analysis of Lane 

Change Crashes (Mar. 2003). We are clearly dealing with a safety issue that requires

regulation by the legislature and, ultimately, law enforcement attention.

I. Trooper Wall’s Interpretation of Section 42-4-903(2) Is 

Arguably Correct

¶32 The majority determines that Trooper Wall did not reasonably enforce subsection 

(2) of section 42-4-903 because the later subsection (4) distinguishes lane changes from 

turns. Maj. op. ¶¶ 23–24. But that distinction is not quite so simple. 
2

¶33 When construing a statute, “[w]e must read the statute as a whole, construing each 

provision consistently and in harmony with the overall statutory design, if possible.” 

Whitaker v. People, 48 P.3d 555, 558 (Colo. 2002). The statute in question is titled “Turning 

movements and required signals,” and it contains five subsections. 

¶34 Subsection (1) explains when a signal must be given, describing situations such as 

turning at an intersection or onto a private road or turning from a direct course or moving 

a vehicle left or right:

No person shall turn a vehicle at an intersection unless the vehicle is in 

proper position upon the roadway as required in section 42-4-901, or turn a 

vehicle to enter a private road or driveway, or otherwise turn a vehicle from 

a direct course or move right or left upon a roadway unless and until such 

movement can be made with reasonable safety and then only after giving 

an appropriate signal in the manner provided in sections 42-4-608 and 

42-4-609.

§ 42-4-903(1) (emphasis added). The plain language of subsection (1) applies to lane 

changes, as a lane change is either “turn[ing] a vehicle from a direct course” or “mov[ing] 

right or left upon a roadway.” Id. Thus, a driver may not change lanes until the lane 

change “can be made with reasonable safety” and the driver has “giv[en] an appropriate 

signal.” Id.

¶35 Subsection (2), without defining what constitutes a “turn,” explains how long a 

signal must be given, and it gives two options based on the car’s location and speed:

A signal of intention to turn right or left shall be given continuously during 

not less than the last one hundred feet traveled by the vehicle before turning 

in urban or metropolitan areas and shall be given continuously for at least 

two hundred feet on all four-lane highways and other highways where the 

prima facie or posted speed limit is more than forty miles per hour.
3

§ 42-4-903(2). Notably, subsection (2) does not require an intention to turn that causes a 

car to leave the highway or even an intention to turn that creates a complete change in 

direction. 

¶36 Subsection (3) explains when signals (brake lights) are required for stops or 

sudden decreases in speed: “No person shall stop or suddenly decrease the speed of a 

vehicle without first giving an appropriate signal in the manner provided in sections 

42-4-608 and 42-4-609 to the driver of any vehicle immediately to the rear when there is 

opportunity to give such signal.” § 42-4-903(3). While not applicable in this situation, as 

the signals referenced are brake lights, this subsection rounds out the situations where 

signals must be used.

¶37 Subsection (4) then explains how such signals should be used as well as how they 

should not be used:

The signals provided for in section 42-4-608(2) shall be used to indicate an 

intention to turn, change lanes, or start from a parked position and shall not 

be flashed on one side only on a parked or disabled vehicle or flashed as a 

courtesy or “do pass” signal to operators of other vehicles approaching 

from the rear.

§ 42-4-903(4). The focus of subsection (4) is on the proper use of signals; they should be 

used to signal an intention to move but should not be used to signal an intention not to 

move. This is a logical provision to include in a signaling statute, as a signal cannot be 

effective if it is used to indicate contrary intentions.

¶38 Finally, subsection (5) explains that “[a]ny person who violates any provision of 

this section commits a class A traffic infraction.” § 42-4-903(5). 
4

¶39 Therefore, section 42-4-903(1) begins by listing the turning movements that require 

a signal, (2) next dictates for how long the signal must be given before so moving, (3) then 

sets forth the rule for when stopping or suddenly slowing requires a signal, (4) 

emphasizes when a signal should not be used, and (5) last sets forth the penalty for 

violations. Thus, when reading the statute as a whole, I do not believe that the legislature 

intended for subsection (4)—which explains when signals should not be used—to limit 

the scope of subsection (2)—which explains for how long signals must be used.

¶40 Moreover, it makes sense to require a signal for an adequate distance before 

changing lanes. If the purpose of a signal is to make other drivers aware of your intention 

to deviate from your current path of travel, requiring you to indicate that intent for a 

specific distance is reasonable regardless of how far off your current path you intend to 

deviate. Accordingly, I believe that Trooper Wall’s interpretation of section 42-4-903(2)—

that it applies to lane changes as well as turns—is arguably correct.

II. Even if Incorrect, Trooper Wall’s Interpretation of 

Section 42-4-903 Is Objectively Reasonable

¶41 Even assuming that Trooper Wall’s interpretation is incorrect (as the majority 

concludes), his interpretation was nevertheless objectively reasonable for two reasons. 

First, the Department of Revenue repeatedly interpreted the statute the same way as 

Trooper Wall when creating its own literature. And second, a federal district court, 

addressing a similar situation, found the same interpretation to be objectively reasonable.

¶42 I begin with the Department of Revenue’s own literature. The Department creates 

such literature to educate the public regarding Colorado traffic laws. And the most recent 
5

edition of the Department’s Colorado Driver Handbook interprets section 42-4-903’s 

signaling requirements exactly as Trooper Wall did: “In urban or metropolitan areas, you 

must signal continuously for 100 feet before making a turn or lane change. On four-lane 

highways, where the posted speed limit is more than 40 mph, you must signal for 200 

feet.” Div. of Motor Vehicles, Colo. Dep’t of Revenue, DR-2337, Colorado Driver Handbook

22 (2017) (emphasis added). This interpretation is consistent throughout the handbook.1 

When discussing turning, the handbook states that “[a]t speeds above 40 mph you must 

signal continuously for 200 feet before making a turn or lane change.” Id. at 21. When 

discussing freeway driving, the handbook reminds drivers to “[s]ignal at least 200 feet 

before you change lanes and avoid frequent lane changes.” Id. at 24. When explaining 

the driving test requirements, the handbook explains that one “performance 

requirement” of signaling on the test is that the driver “activates [the] signal the proper 

distance in advance of turning or making a lane change.” Id. at 32.

¶43 The majority is correct that whether Trooper Wall read the Department of 

Revenue’s driver handbook is irrelevant, as it would relate to Trooper Wall’s subjective

understanding of the statute. Maj. op. ¶ 27. The majority is also correct that the handbook 

does not supersede Colorado’s statutory law. Id. Nevertheless, the interpretation in the 

 

1 The previous edition of the Colorado Driver Handbook contained the same interpretation. 

See Div. of Motor Vehicles, Colo. Dep’t of Revenue, DR-2337, Colorado Driver Handbook

18, 21, 27 (2012).
6

handbook is relevant to whether Trooper Wall’s interpretation of section 42-4-903(2) was 

objectively reasonable.

¶44 Giving further support to the objective reasonableness of Trooper Wall’s 

interpretation is the U.S. District Court’s reasoning in United States v. Rubio-Sepulveda, 237 

F. Supp. 3d 1116 (D. Colo. 2017), appeal docketed, No. 18-1055 (10th Cir. Feb. 13, 2018). In 

that case, an officer interpreted section 42-4-903(2) in the same manner as Trooper Wall.

Id. at 1122 n.4. The federal district court, relying on Heien, found that the officer’s 

interpretation was mistaken but objectively reasonable. Id. In doing so, the federal 

district court distinguished a Fifth Circuit case, which held “that the officer’s mistaken 

interpretation of a similar Texas turn signal provision was not a reasonable mistake of 

law in part because (1) the Texas Driver’s Manuel [sic] supported an interpretation 

contrary to the officer’s, i.e. supported a plain reading of the statutory provision, and (2) 

the Texas Court of Appeals had recently clarified the issue.” Id. (citing United States v. 

Alvarado-Zarza, 782 F.3d 246, 250 (5th Cir. 2015)). Remarkably, our situation here is the 

complete opposite. Colorado’s driver handbook supports Trooper Wall’s interpretation 

of the statute. And, finally, at the time of Trooper Wall’s actions, no Colorado appellate 

court had interpreted section 42-4-903(2) in any way, let alone in a way that says the 

signaling requirements do not apply to lane changes.

2

 

2 The defense argues that “even if section 42-4-903 could have been construed as 

ambiguous before Rubio-Sepulveda was issued, that opinion put officers on notice that 

section 42-4-903(2) does not apply to lane changes.” Answer Br. at 17. While the Rubio-
7

¶45 Trooper Wall interpreted section 42-4-903(2) the same way the Department of 

Revenue has been interpreting it for at least six years and in a manner that a different 

court found objectively reasonable. As such, even if Trooper Wall’s interpretation was 

incorrect, it was objectively reasonable.

III. The Exclusionary Rule Should Not Apply

¶46 The majority today determines that there was a Fourth Amendment violation, but 

it declines to address whether suppression is warranted because the People framed the 

issue around Trooper Wall’s objective reasonableness. This misses the point. In affirming 

the trial court’s suppression order, the majority is implicitly affirming the trial court’s 

determination that suppression was warranted. In fact, the notice of appeal states: “This 

interlocutory appeal is of the district court’s ruling suppressing the evidence obtained as a 

result of the traffic stop.” Notice of Appeal at 3 (emphasis added). Additionally, in the 

People’s opening brief, they explain that “[t]he issue to be decided [is] whether the district 

court erred in granting defendant’s motion to suppress evidence.” Opening Br. at 7. 

Thus, in refusing to consider whether the exclusionary rule should apply, the majority 

misses the central question raised in this case.

 

Sepulveda Court found the officer’s reading of the statute to be mistaken, it reached that 

conclusion in a footnote. Despite that footnote, the court relied on a different theory 

altogether to hold that the stop was legal. Rubio-Sepulveda, 237 F. Supp. 3d at 1122 n.4. 

As such, the court’s interpretation of the statute is dicta. While I hold law enforcement 

to a high standard and expect officers to know the law, to conclude that this trooper acted 

objectively unreasonably because he was put on notice by an arguably irrelevant footnote 

in a non-binding case is unrealistic.
8

¶47 At the end of the day, the question of whether the exclusionary rule should apply 

comes down to whether the officer’s misconduct can and should be effectively deterred. 

“[T]he exclusionary rule should not automatically apply every time a Fourth Amendment 

violation is found; rather, it should apply only in those circumstances where its remedial 

objectives are actually served by suppression.” People v. Gutierrez, 222 P.3d 925, 941 (Colo. 

2009). “[T]he deterrence benefits of exclusion, and thus the [exclusionary] rule’s 

application, depend on the culpability of the law enforcement conduct at issue.” Casillas 

v. People, 2018 CO 78M, ¶ 34, 427 P.3d 804, 813. “Because the exclusionary rule ‘serves to 

deter deliberate, reckless, or grossly negligent conduct, or in some circumstances 

recurring or systemic negligence,’ to warrant its application, law enforcement conduct 

must be ‘sufficiently deliberate that exclusion can meaningfully deter it, and sufficiently 

culpable that such deterrence is worth the price paid by the justice system.’” Id. at ¶ 22, 

427 P.3d at 810 (quoting Herring v. United States, 555 U.S. 135, 144 (2009)). Thus, the 

deterrence value of merely negligent conduct is not sufficient to warrant the cost of the 

exclusionary rule. See Herring, 555 U.S. at 147–48 (“[W]hen police mistakes are the result 

of negligence . . . rather than systemic error or reckless disregard of constitutional 

requirements, any marginal deterrence does not ‘pay its way.’” (quoting United States v. 

Leon, 468 U.S. 897, 907 n.6 (1984))).

¶48 Therefore, even were I to accept the majority’s conclusion that Trooper Wall’s 

interpretation was objectively unreasonable, that conclusion does not warrant 

suppression here. Mere negligence is insufficient to invoke the exclusionary rule; and, 
9

the majority does not identify anything about Trooper Wall’s conduct that rose to the 

level of gross negligence, thus making it “sufficiently culpable” such that the 

exclusionary rule should apply. 

¶49 Trooper Wall’s interpretation of the statute is arguably a safer interpretation of the 

law. The question of whether lane changes are in fact “turns” is more nuanced than the 

majority gives it credit for, as evidenced by the Department of Revenue’s own 

publication. Moreover, the federal district court in Rubio-Sepulveda found that the same 

interpretation, under similar circumstances, did not rise even to the level of ordinary 

negligence, let alone gross negligence.

Conclusion

¶50 I believe that Trooper Wall’s interpretation of the statute was correct. Even if his 

interpretation was incorrect, however, it was objectively reasonable. And even if his 

interpretation was objectively unreasonable, his conduct did not rise to the level of gross 

negligence that is required to apply the exclusionary rule. As such, I would reverse the 

trial court’s suppression order. Accordingly, I respectfully dissent.

I am authorized to state that CHIEF JUSTICE COATS joins in this dissent.