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DUI LIBRARY | Traffic Stops (Updated 2019)


Traffic Stops


Most DUI cases start with a traffic stop by the police. A traffic stop is a seizure which triggers your Fourth Amendment protections.  Thus, the analysis of any DUI cases usually begins by asking: did the police have a legal justification for making that seizure?

Traffic Stop DUI Arizona

Motions to Suppress Based on an Illegal Traffic Stop

The General Rule

You have an expectation of privacy driving your car.  Similar to the expectation of privacy as to what is in your pockets while walking down the street.  Accordingly, to be pulled over by the police, even for temporary detention, the government must reasonable suspension that you violated the law.

Constitutional Protections

The Fourth Amendment prohibits unreasonable searches and seizures. U.S. Const. amend. IV.


Section 8. No person shall be disturbed in his private affairs, or his home invaded, without authority of law.



State v. Johnson, 220 Ariz. 551, 557, ¶ 13, 207 P.3d 804, 810 (App. 2009)

  • But we find no authority holding Arizona’s right to privacy outside the context of home searches to be broader in scope than the corresponding right to privacy in the United States Constitution. See generally State v. Juarez, 203 Ariz. 441, ¶¶ 14–16, 55 P.3d 784, 787–88 (App.2002) (citing cases).
  • And, in addressing an automobile search, our supreme court long ago stated that article II, § 8, “although different in its language, is of the same general effect and purpose as the Fourth Amendment, and, for that reason, decisions on the right of search under the latter are well in point.” Malmin v. State, 30 Ariz. 258, 261, 246 P. 548, 548–49 (1926); see also State v. Reyna, 205 Ariz. 374, ¶ 14 & n. 5, 71 P.3d 366, 369–70 & n. 5 (App.2003) (“[W]e do not read the court’s decisions concerning home searches as evidencing a state-law departure from Fourth Amendment principles governing vehicle searches.”).
  • Similarly, Division One of this court has declined to find that Arizona’s constitution provides greater protection than the Fourth Amendment for lawfully stopped drivers. See State v. Teagle, 217 Ariz. 17, n. 3, 170 P.3d 266, 271 n. 3 (App.2007).
  • Although Johnson identifies other states that have found greater protection in their state constitutions for lawfully stopped passengers, our jurisprudence has consistently found our constitutional protections to parallel those provided by the Fourth Amendment. See Reyna, 205 Ariz. 374, ¶ 14, 71 P.3d at 369 (“Our supreme court long ago held that Article 2, Section 8 of the Arizona Constitution ‘is of the same general effect and purpose as the Fourth Amendment’ and that the decisions concerning the scope of allowable vehicle searches under the federal constitution are ‘well on point’ in deciding cases under the Arizona Constitution.”), quoting Malmin, 30 Ariz. at 261, 246 P. at 549.

Relevant Arizona Law

(a) Definition. For purposes of this rule, “suppress” refers to the exclusion of evidence that was unlawfully obtained due to a constitutional violation.
Ariz. R. Crim. P. 16.2

(b) Burden of Proof on Pretrial Motions to Suppress Evidence.

1) Generally. Subject to (b)(2), the State has the burden of proving by a preponderance of the evidence the lawfulness in all respects of the acquisition of all evidence that the State will use at trial.
(2) Defendant’s Burden.  If any of the conditions listed below are present, the State’s burden of proof under (b)(1) arises only after the defendant alleges specific circumstances and establishes a prima facie case supporting the suppression of the evidence at issue:
(A) the evidence involves a confession, identification, search, or seizure, and the defendant is entitled under Rule 15 to discover how the evidence was obtained;
(B) defense counsel was present when the evidence was taken; or
(C) the evidence was obtained under a warrant.
Ariz. R. Crim. P. 16.2

  • State v. Hyde, 186 Ariz. 252, 921 P.2d 655 (1996) certiorari denied 117 S.Ct. 1091, 519 U.S. 1153, 137 L.Ed.2d 224. “Burden of going forward” requires the party that bears it to produce sufficient preliminary evidence before the party with the burden of persuasion must proceed with its evidence, and failure to meet the burden of going forward results in an adverse ruling before the presentation of evidence by a party with the burden of persuasion. 
  • State v. Rodriguez,  126 Ariz. 28, 612 P.2d 484 (1980).  A motion “in limine” meaning “on or at the threshold;  at the very beginning;  preliminarily”, is not provided for by name in either criminal or civil rules of procedure, but the motion is frequently used to exclude anticipated prejudicial evidence before the evidence is actually offered by the opposing party.  
  • State v. Superior Court of State of Ariz., In and For Pima County, 128 Ariz. 583, 627 P.2d 1081 (1981).  In criminal cases, a motion in limine is treated as a motion to suppress, and the ruling of the trial court will not be disturbed on appeal absent a clear abuse of discretion.

State v. Nadler, 129 Ariz. 19, 628 P.2d 56 (App. 1981). A defendant may testify in support of a motion to suppress in order to establish his interest in contraband and, in such event, his testimony cannot be admitted as evidence of guilt at trial

§ 28-1594. Authority to detain persons
A peace officer or duly authorized agent of a traffic enforcement agency may stop and detain a person as is reasonably necessary to investigate an actual or suspected violation of this title and to serve a copy of the traffic complaint for an alleged civil or criminal violation of this title.

§ 28-729. Driving on roadways laned for traffic

If a roadway is divided into two or more clearly marked lanes for traffic, the following rules in addition to all others consistent with this section apply:
1. A person shall drive a vehicle as nearly as practicable entirely within a single lane and shall not move the vehicle from that lane until the driver has first ascertained that the movement can be made with safety.
2. On a roadway that is divided into three lanes, a person shall not drive a vehicle in the center lane except when overtaking and passing another vehicle where the roadway is clearly visible and the center lane is clear of traffic within a safe distance, or in preparation for a left turn or where the center lane is at the time allocated exclusively to traffic moving in the direction the vehicle is proceeding and is signposted to give notice of the allocation.
3. Official signs may be erected directing slow-moving traffic to use a designated lane or designating those lanes to be used by traffic moving in a particular direction regardless of the center of the roadway, and drivers of vehicles shall obey the directions of every sign. 

  • State v. Livingston, 206 Ariz. 145, 75 P.3d 1103 (App. 2003), review denied.  Defendant’s isolated and minor crossing of shoulder line of highway did not amount to conduct prohibited by statute, and thus police officer lacked reasonable basis to stop defendant’s automobile.
  • Bliss v. Treece134 Ariz. 516, 658 P.2d 169 (1983).  Former section providing that a vehicle shall not be moved from a lane until the driver has first ascertained that the movement can be made with safety excludes from its reach those movements which are beyond the driver’s control.  

§ 13-3883. Arrest by officer without warrant:


B. A peace officer may stop and detain a person as is reasonably necessary to investigate an actual or suspected violation of any traffic law committed in the officer’s presence and may serve a copy of the traffic complaint for any alleged civil or criminal traffic violation. A peace officer who serves a copy of the traffic complaint shall do so within a reasonable time of the alleged criminal or civil traffic violation.

State v. Moreno, 236 Ariz. 347, 351, ¶ 9, 340 P.3d 426, 430 (App. 2014)

  • Moreno acknowledges the detective accurately related the law; however, he contends that by initially determining the Concord’s window tint allowed for transmission of less than the permitted amount of light, the detective “erroneously conclud[ed] the legal effects of believed facts.”
  • …because the detective observed legal tint, but perceived it to be illegal, he misapprehended the law. We find this argument unpersuasive and illogical. Under this reasoning, a stop based on a tint violation where the tint later proved to be within legal limits would always constitute a mistake of law.
  • The detective’s mistake, however, was not a result of misapplication or misunderstanding of the law. Instead, he incorrectly estimated the opacity of the tint on the Concord’s windows; had the opacity been as the detective believed, it would have violated A.R.S. § 28–959.01(A)(1).  Thus, the trial court correctly found that the detective made a mistake of fact regarding the window tint.


  • We therefore need only consider whether the detective’s mistaken belief that the Concord’s window had illegal tint was reasonable. See id. at 539–40 (Fourth Amendment tolerates only objectively reasonable mistakes).


  • Moreno is correct that an officer must have an objective and particularized basis for conducting a traffic stop based on a suspected window tint violation.
  • We disagree, however, with his characterization of “objective basis” as requiring some measurable proof of a violation before conducting a traffic stop.


  • Nor do we agree with Moreno that the “particularized” requirement was not met because the detective failed to “mention or describe in detail” the factors that caused him to suspect the window tint was illegal. A suspicion must “be particularized such that it does more than simply describe large numbers of others who are also driving on the highways in that vicinity and at that time.” Gonzalez–Gutierrez, 187 Ariz. at 120, 927 P.2d at 780. But reasonable suspicion does not require police to rule out every possibility of innocent conduct. State v. Ramsey, 223 Ariz. 480, ¶ 23, 224 P.3d 977, 982 (App.2010).


  • Here, the detective had a reasonable and good-faith suspicion that the Concord’s front-side windows were in violation of § 28–959.01(A)(1).   He observed the window tint on a “sunny” day, and determined that it “appeared to be illegal” because it was “too dark.”   He also had accurate knowledge of Arizona’s law on window tint, and testified that over the course of his career he had stopped “several hundreds” of vehicles based on suspected tint violations, and had been correct “99 percent” of the time.  
  • He explained he was able to estimate his accuracy because he “always test[s] the window with [a] tint meter” after making a traffic stop based on a tint violation.
  • Notably, the Concord window was near the darkest legal limit, and the detective was only off in his visual assessment by a few degrees of light transmission.
  • When all the above factors are considered together, particularly in light of the detective’s substantial experience with tint violations, we cannot say the trial court erred in finding the detective had a good-faith, reasonable basis for suspecting the Concord’s window tint was illegal.


State v. Moran, 232 Ariz. 528, 307 P.3d 95 (App. 2013)

  • Officer’s visual estimation that defendant’s vehicle was driving 50 miles per hour (MPH) in a 35 MPH zone provided reasonable suspicion for a traffic stop for speeding, where the officer had been trained to accurately estimate a vehicle’s speed within 5 miles per hour.

§ 28-754. Turning movements and required signals
A. A person shall not turn a vehicle at an intersection unless the vehicle is in proper position on the roadway as required in § 28-751, 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 on a roadway unless and until the movement can be made with reasonable safety. A person shall not so turn any vehicle without giving an appropriate signal in the manner provided by this article in the event any other traffic may be affected by the movement.

B. A signal of intention to turn right or left when required shall be given continuously during not less than the last one hundred feet traveled by the vehicle before turning.

C. A person shall not stop or suddenly decrease the speed of a vehicle without first giving an appropriate signal in the manner provided by this article to the driver of any vehicle immediately to the rear when there is opportunity to give the signal.

  • State v. Salcido, 238 Ariz. 461, 362 P.3d 508 (App. 2015), review denied. Police had reasonable suspicion to conduct a traffic stop based on defendant’s illegal lane change, where officer testified that defendant had changed lanes without signaling, had “cut” him “off,” and had been all over the road.


Traffic Stop Cases - Outside of Arizona


Oregon Supreme Court

Issue: During a traffic stop, does a police officer asking if a driver has guns and drugs, violate Article I, section 9, of the Oregon Constitution?  

Answer:  Yes.  Because the traffic stop had nothing to do with guns or drugs the officer’s questions expanded the permissible scope of the traffic stop.  Those questions had nothing to do with the purpose of the stop. 

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