DANIEL KELLY, J.
¶ 1. A law enforcement officer discovered a cache of controlled substances when he performed a warrantless—but allegedly consensual— search of Lewis O. Floyd, Jr. during a traffic stop. Mr. [402]*402Floyd says that because the officer extended the traffic stop without the necessary reasonable suspicion, his alleged "consent" was void and the evidence obtained from the search should have been suppressed. Mr. Floyd also says he received ineffective assistance of counsel at the suppression hearing because his trial counsel failed to present testimony Mr. Floyd believes would have established he was not asked to consent to a search.1
I. BACKGROUND
A. The Traffic Stop
f 2. On an early July evening in 2013, Deputy Troy Ruffalo of the Racine County Sheriffs Office stopped Mr. Floyd near 16th and Racine Streets in the City of Racine because his car registration had been suspended for emissions violations. Deputy Ruffalo, a six-year veteran law enforcement officer, believed this to be a "high crime" part of the city known for frequent drug and gang activity.
f 3. When Deputy Ruffalo approached Mr. Floyd's car, he noted it had tinted windows and "air fresheners in every vent of the vehicle as well as hanging off the rear view mirror and air fresheners up on the — where the vents were." This, he said, is often an indicator of drug-related activity because "[ujsually [403]*403the air fresheners or the amount of them are — is an agent that is used to mask the smell of narcotics."2
¶ 4. Deputy Buffalo's initial contact with Mr. Floyd lasted approximately two to three minutes, during which he discovered Mr. Floyd had no driver's license or insurance information with him. After obtaining Mr. Floyd's Wisconsin State identification card, Deputy Ruffalo returned to his squad car to draft Mr. Floyd's citations and contact dispatch to ask for a canine unit or other "cover" squad. No canine units were available, and Officer Aaron White, an officer with the City of Racine Police Department, arrived on the scene while Deputy Ruffalo was completing Mr. Floyd's citations.
f 5. Deputy Ruffalo reestablished contact with Mr. Floyd approximately five or six minutes after pulling him over and, while maintaining possession of Mr. Floyd's identification card and the multiple citations, asked Mr. Floyd to exit the vehicle so he could explain the citations. After Mr. Floyd complied, Deputy Ruffalo asked him if he had any weapons or anything that could harm him. After Mr. Floyd indicated he did not, Deputy Ruffalo asked if he could perform a search for his safety. Mr. Floyd responded "yes, go ahead."3 During the ensuing search, Deputy Ruffalo discovered the illegal drugs that led to the charges in this case.
B. Procedural Background
¶ 6. The State filed a criminal complaint against Mr. Floyd alleging: (1) possession with intent to de[404]*404liver non-narcotic controlled substances, second and subsequent offense; (2) misdemeanor bail jumping, repeater; (3) possession with intent to deliver or manufacture THC = < 200 GMS, second and subsequent offense; and (4) misdemeanor bail jumping, repeater. The subsequent Information alleged the same four counts.
¶ 7. Mr. Floyd moved to suppress the evidence seized during the search, but the circuit court denied the motion. It found that at the time Deputy Ruffalo contacted dispatch for backup, he had suspicions Mr. Floyd was involved in criminal drug-related activity based on several factors, including the numerous air fresheners and the vehicle's tinted windows. It also found that Deputy Ruffalo did not unnecessarily prolong the traffic stop by requesting backup because the cover squad arrived while he was in the process of drafting the citations—a process that took only five to six minutes. The circuit court accepted Deputy Ruffa-lo's explanation that having Mr. Floyd step out of his vehicle was important because he did not have a valid driver's license and therefore could not drive away when the traffic stop ended.
¶ 8. Mr. Floyd pled no-contest to possession with intent to deliver non-narcotic controlled substances as a repeat offender. He moved for postconviction relief, alleging his trial counsel was ineffective for failing to present evidence at the suppression hearing that (he says) would have proved Deputy Ruffalo did not ask for his consent to perform the search. The circuit court observed that Officer White's testimony showed "some dichotomy" with respect to whether Deputy Ruffalo had asked for Mr. Floyd's consent to the search or instead had advised him it was going to happen. Ultimately, the circuit court found Deputy Ruffalo did, in fact, ask Mr. Floyd whether he would consent to the [405]*405search. Thus, the court concluded Mr. Floyd did not receive ineffective assistance of counsel because the testimony was insufficient to demonstrate he had not consented to the search, and so denied the motion.
¶ 9. The court of appeals affirmed in a published opinion, concluding that denial of the suppression motion was proper because Mr. Floyd was lawfully detained when Deputy Ruffalo asked to search him and Mr. Floyd voluntarily consented to the search. See State v. Floyd, 2016 WI App 64, ¶¶ 12, 20, 371 Wis. 2d 404, 885 N.W.2d 156. Relying on Pennsylvania v. Mimms, 434 U.S. 106 (1977) (per curiam), the court of appeals concluded that Deputy Ruffalo's request that Mr. Floyd exit his vehicle during the ongoing traffic stop was per se lawful, and it also pointed out that Mr. Floyd could not drive away because he did not have a valid driver's license. Floyd, 371 Wis. 2d 404, ¶ 12. The court of appeals further held that even if Deputy Ruffalo had extended the traffic stop, the extension was nevertheless reasonable because Deputy Ruffalo reasonably suspected criminal drug-related activity. Id., ¶ 13. As to the postconviction motion, the court of appeals determined there was no reasonable probability the result at the suppression hearing would have been any different had Officer White been called to testify; therefore, it affirmed the circuit court's denial of the postconviction motion. Id., ¶ 27.
¶ 10. We accepted Mr. Floyd's petition for review and now affirm the decision of the court of appeals.
II. STANDARD OF REVIEW
¶ 11. "Whether evidence should be suppressed is a question of constitutional fact." State v. Knapp, 2005 WI 127, ¶ 19, 285 Wis. 2d 86, 700 N.W.2d 899 (quoting [406]*406State v. Samuel, 2002 WI 34, ¶ 15, 252 Wis. 2d 26, 643 N.W.2d 423). We review the circuit court's findings of historical fact under the clearly erroneous standard. State v. Turner, 136 Wis. 2d 333, 343-44, 401 N.W.2d 827 (1987). But the circuit court's application of the historical facts to constitutional principles is a question of law we review independently. Id. While we are not bound by the circuit court's or court of appeals' decisions on questions of law, we benefit from their analyses. State v. Kyles, 2004 WI 15, ¶ 7, 269 Wis. 2d 1, 675 N.W.2d 449.
¶ 12. We review the voluntariness of consent to a search in a similar fashion. See State v. Artic, 2010 WI 83, ¶ 23, 327 Wis. 2d 392, 786 N.W.2d 430. We review the circuit court's findings of historical fact to determine whether they are clearly erroneous. Id. We then independently apply constitutional principles to those facts. Id.
¶ 13. Whether trial counsel's actions constitute ineffective assistance of counsel presents a mixed question of fact and law. State v. Tourville, 2016 WI 17, ¶ 16, 367 Wis. 2d 285, 876 N.W.2d 735. We will not reverse the circuit court's findings of fact unless they are clearly erroneous. Id. However, we independently review, as a matter of law, whether those facts demonstrate ineffective assistance of counsel. Id.
III. DISCUSSION
¶ 14. We must determine whether the drug-disclosing search of Mr. Floyd was consonant with the constitutional mandate that we be free of unreasonable searches and seizures. The State says the search [407]*407was proper because it occurred during a lawful traffic stop and Mr. Floyd consented to it. Mr. Floyd says this is not so—the search took place after the traffic stop should have ended, and so he was unlawfully seized when it took place, which rendered any alleged "consent" void as a matter of law. In any event, he says, he did not actually consent to the search, and if his counsel had not been ineffective the court would have heard testimony to prove that point.
¶ 15. The disagreement between the State and Mr. Floyd is really quite narrow, although no less important for that. The parties agree that Mr. Floyd's expired tags provided a sufficient basis for Deputy Ruffalo to initiate the traffic stop. And Mr. Floyd did not contest an officer's authority to ask a driver to exit his vehicle during such an encounter. Nor did he offer any argument against an officer's authority to ask a lawfully-seized person to consent to a search. Their disagreement centers on where we draw the line separating traffic stops of acceptable duration from those that have been impermissibly extended. A motorist is lawfully seized during the proper duration of a traffic stop, but unlawfully seized if it lasts longer than necessary to complete the purpose of the stop. So the location of the line is important because of the constitutional rights affected. As we discuss below, if Mr. Floyd was unlawfully seized when Deputy Ruffalo requested permission to search him, his "consent" would be constitutionally invalid, and the evidence discovered during the search would need to be suppressed.
¶ 16. Mr. Floyd says the court of appeals drew the line in the wrong place. He argues that when Deputy Ruffalo finished writing the citations, the Constitution permitted no further interaction between the [408]*408two of them beyond Deputy Ruffalo explaining the citations and informing him he was free to go. So when Deputy Ruffalo instead asked him if he would consent to a search, Mr. Floyd says Deputy Ruffalo extended the traffic stop with no justifiable basis.
¶ 17. The State says the constitutionally-permissible duration of the traffic stop did not conclude before Deputy Ruffalo asked Mr. Floyd if he would consent to a search. Thus, as the fruit of a consensual search, the illegal drugs comprised proper evidence against Mr. Floyd. And even if Deputy Ruffalo extended the stop, the State says, the totality of the circumstances gave him reasonable suspicion to believe Mr. Floyd had committed, was committing, or was about to commit a crime.
¶ 18. Thus, our task is to espy the point at which the traffic stop should have ended and assess how the search related to that point. Because the purpose of the stop determines its proper scope, we must identify what an officer may lawfully do when detaining someone for a suspended vehicle registration. See, e.g., Rodriguez v. United States, 575 U.S. _, 135 S. Ct. 1609, 1614 (2015) ("the tolerable duration of police inquiries in the traffic-stop context is determined by the seizure's 'mission'—to address the traffic violation that warranted the stop, . . . and attend to related safety concerns .... Authority for the seizure thus ends when tasks tied to the traffic infraction are—or reasonably should have been—completed." (internal citations omitted)).
[409]*409A. Constitutional Implications Of Traffic Stops
f 19. We begin where we should, with the constitutional prohibitions against unreasonable searches and seizures. The Fourth Amendment to the United States Constitution says:
The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.
U.S. Const. amend. IV. Its Wisconsin counterpart, found in Article I, section 11 of the Wisconsin Constitution,4 is substantively identical, and we normally interpret it coextensively with the United States Supreme Court's interpretation of the Fourth Amendment. See, e.g., State v. Dumstrey,, 2016 WI 3, ¶ 14, 366 Wis. 2d 64, 873 N.W.2d 502 (citing State v. Arias, 2008 WI 84, ¶ 20, 311 Wis. 2d 358, 752 N.W.2d 748).
¶ 20. It is an unremarkable truism that a traffic stop is a seizure within the meaning of our Constitutions. " 'The temporary detention of individuals during the stop of an automobile by the police, even if only for a brief period and for a limited purpose, constitutes a seizure of persons within the meaning of the Fourth [410]*410Amendment.'" State v. Popke, 2009 WI 37, ¶ 11, 317 Wis. 2d 118, 765 N.W.2d 569 (citations and one set of quotations omitted). Reasonable suspicion that a driver is violating a traffic law is sufficient to initiate a traffic stop. State v. Houghton, 2015 WI 79, ¶ 30, 364 Wis. 2d 234, 868 N.W.2d 143 ("[R]easonable suspicion that a traffic law has been or is being violated is sufficient to justify all traffic stops."). Reasonable suspicion requires that "[t]he officer must be able to point to specific and articulable facts which, taken together with rational inferences from those facts, reasonably warrant the intrusion of the stop." Popke, 317 Wis. 2d 118, f 23 (two sets of quotation marks and citation omitted).
¶ 21. Traffic stops are meant to be brief interactions with law enforcement officers, and they may last no longer than required to address the circumstances that make them necessary. "A routine traffic stop ... is a relatively brief encounter and 'is more analogous to a so-called Terry[5] stop . . . than to a formal arrest.' " Knowles v. Iowa, 525 U.S. 113, 117 (quoting Berkemer v. McCarty, 468 U.S. 420, 439 (1984)) (footnote added; second ellipses in Knowles; one set of quotation marks omitted). "Because addressing the infraction is the purpose of the stop, it may 'last no longer than is necessary to effectuate th[at] purpose.' " Rodriguez, 135 S. Ct. at 1614 (citation omitted; alteration in Rodriguez). "Authority for the seizure thus ends when tasks tied to the traffic infraction are—or reasonably should have been—completed." Id.
[411]*411f 22. Thus, we draw the line between traffic stops of proper duration and those that extend into unconstitutional territory according to functional considerations. We assess those considerations in the context of the "totality of the circumstances." See, e.g., United States v. Everett, 601 F.3d 484, 493—94 (6th Cir. 2010). And while the temporal duration of the stop may inform those considerations, it is not in itself disposi-tive. See United States v. Sharpe, 470 U.S. 675, 686 ("In assessing whether a detention is too long in duration to be justified as an investigative stop, we consider it appropriate to examine whether the police diligently pursued a means of investigation that was likely to confirm or dispel their suspicions quickly, during which time it was necessary to detain the defendant."); see also United States v. Peralez, 526 F.3d 1115, 1119 (8th Cir. 2008) ("Whether a traffic stop 'is reasonable in length is a fact intensive question, and there is no per se time limit on all traffic stops.'" (citation omitted)). Generally speaking, an officer is on the proper side of the line so long as the incidents necessary to carry out the purpose of the traffic stop have not been completed, and the officer has not unnecessarily delayed the performance of those incidents. See, e.g., Rodriguez, 135 S. Ct. at 1614-15 (explaining that authority for a traffic-stop based seizure ends when tasks related to the infraction are, or should have been, completed). He steps across that line (again speaking generally) when he maintains the seizure after he has completed all the necessary functions attendant on the traffic stop. See State v. Malone, 2004 WI 108, ¶ 26, 274 Wis. 2d 540, 683 N.W.2d 1 (a reasonable seizure can become unreasonable if the [412]*412officer "extends the stop beyond the time necessary to fulfill the purpose of the stop." (citation omitted)).
¶ 23. Mr. Floyd's stop was not complicated—his vehicle's registration was suspended. Deputy Ruffalo then learned Mr. Floyd had neither insurance nor a valid driver's license. At a minimum, this authorized Deputy Ruffalo to take the time reasonably necessary to draft the appropriate citations and explain them to Mr. Floyd. See, e.g., Rodriguez, 135 S. Ct. at 1614 (explaining that in the traffic stop context, "addressing the infraction is the purpose of the stop . . . ."). Until that is done, and so long as Deputy Ruffalo does not unnecessarily delay the process, the permissible duration of the traffic stop has not elapsed. Id. at 1615 ("The seizure remains lawful only 'so long as [unrelated] inquiries do not measurably extend the duration of the stop.' " (quoting Arizona v. Johnson 555 U.S. 323, 333 (2009); alteration in Rodriguez)).
¶ 24. We note that before Deputy Ruffalo asked Mr. Floyd to consent to a search, he asked him to step out of his vehicle. During a valid traffic stop, this is a matter of no constitutional moment: "[0]nce a motor vehicle has been lawfully detained for a traffic violation, the police officers may order the driver to get out of the vehicle without violating the Fourth Amendment's proscription of unreasonable searches and seizures." Mimms, 434 U.S. at 111 n.6. In an area of the law where bright lines are rare, we have had no difficulty discerning one here. In State v. Johnson we recognized that Mimms "established a per se rule that an officer may order a person out of his or her vehicle incident to an otherwise valid stop for a traffic violation." 2007 WI 32, ¶ 23, 299 Wis. 2d 675, 729 N.W.2d 182.
[413]*413¶ 25. That brings us to the nub of the dispute between the State and Mr. Floyd. After writing the citations, Deputy Ruffalo returned to Mr. Floyd's car and asked him if he would submit to a search. Mr. Floyd says this request extended the stop beyond its permissible duration. The only thing Deputy Ruffalo could lawfully do after writing the citations, Mr. Floyd says, was explain them to him and bid him good day.
¶ 26. Although Mr. Floyd's argument incorporates the principle that the "mission" of the traffic stop defines its acceptable duration, he does not account for how the officer's safety fits within that mission. "Traffic stops are 'especially fraught with danger to police officers ....'" Rodriguez, 135 S. Ct. at 1616 (quoting Johnson, 555 U.S. at 330); see also Mimms, 434 U.S. at 110 ("We think it too plain for argument that the State's proffered justification—the safety of the officer —is both legitimate and weighty."). That makes officer safety an integral part of every traffic stop's mission. Rodriguez, 135 S. Ct. at 1616 ("Unlike a general interest in criminal enforcement, however, the government's officer safety interest stems from the mission of the stop itself.")
¶ 27. The danger inherent to traffic stops authorizes an officer "to take certain negligibly burdensome precautions in order to complete his mission safely." Id.; see also Mimms, 434 U.S. at 110-11 (discussing inherent risks a police officer faces during a traffic stop, such as assault by seated suspects and accidental injury from passing traffic, in concluding the request that a person exit the vehicle during a traffic stop is justifiable and de minimis)', Johnson, 299 Wis. 2d 675, ¶¶ 25-27, (acknowledging "the serious risks law enforcement officers must undertake whenever they ini[414]*414tiate contact with a suspect who is seated in a vehicle"). Thus, the questions to which Mr. Floyd objects are appropriate if they are negligibly burdensome precautions to ensure the officer's safety during the stop.
¶ 28. Deputy Ruffalo asked Mr. Floyd if he had any weapons or anything that could harm him. When Mr. Floyd said he didn't, Deputy Ruffalo asked if he could perform a search for his safety. Both questions specifically related to the officer's safety. According to Mr. Floyd, however, the second question was not negligibly burdensome: "What the State entirely ignores is that unlike questions seeking information, a request to conduct a frisk involves 'a severe, though brief, intrusion upon cherished personal security . . . [that] must surely be an annoying, frightening, and perhaps humiliating experience.' " (Quoting Terry v. Ohio, 392 U.S. 1, 24-25 (1968)). While it is true that such a search can be all of that, a request to conduct such a search cannot. In fact, that request is just like "questions seeking information" because it is just seeking information—to wit, whether Mr. Floyd would agree to be searched. What follows the answer to the question may be a non-negligible burden, but that says nothing about the nature of the question itself. Mr. Floyd provided no other argument that the questions imposed a burden forbidden by Rodriguez, and nothing about them immediately suggests a disqualifying characteristic. Therefore, because the questions related to [415]*415officer safety and were negligibly burdensome, they were part of the traffic stop's mission, and so did not cause an extension.6
B. Constitutional Consent
¶ 29. Whatever additional time the actual search consumed, or the burden it imposed, is irrelevant so long as Mr. Floyd consented to it. Schneckloth v. Bustamonte, 412 U.S. 218, 242-43 (1973) ("While the Fourth and Fourteenth Amendments limit the circumstances under which the police can conduct a search, there is nothing constitutionally suspect in a person's voluntarily allowing a search."). When we inquire into the legitimate scope of a traffic stop's mission, its duration, and the burdensomeness of its incidents, we do so [416]*416because these are nonconsensual aspects of the interaction between a citizen and a law enforcement officer. But when a person consents, the Fourth Amendment does not bar the search (so long as it does not exceed the scope of the person's consent). Illinois v. Rodriguez, 497 U.S. 177, 181 (1990) (explaining that although the Fourth Amendment generally prohibits warrantless searches, "[t]he prohibition does not apply ... to situations in which voluntary consent has been obtained . ..."); see also Schneckloth, 412 U.S. at 219 ("It is equally well settled that one of the specifically established exceptions to the requirements of both a warrant and probable cause is a search that is conducted pursuant to consent."); United States v. Strickland, 902 F.2d 937, 941 (11th Cir. 1990) ("When an individual gives a general statement of consent without express limitations, the scope of a permissible search is not limitless. Rather it is constrained by the bounds of reasonableness: what a police officer could reasonably interpret the consent to encompass."). Thus, we inquire now into whether Mr. Floyd provided constitutionally-valid consent to Deputy Ruffalo's search.
¶ 30. The circuit court found that after Deputy Ruffalo asked whether Mr. Floyd would consent to a search, Mr. Floyd said "yes, go ahead." This is an unequivocal assent, and so it is sufficient to authorize the search so long as Mr. Floyd's response was given "freely and voluntarily." Johnson, 299 Wis. 2d 675, ¶ 16 ("When the purported legality of a warrantless search is based on the consent of the defendant, that consent must be freely and voluntarily given."). The State bears the burden of establishing by clear and convincing evidence that a person's consent to a search was voluntary. State v. Phillips, 218 Wis. 2d 180, 197, [417]*417577 N.W.2d 794 (1998). Generally, a response is voluntary if it "was given in the absence of duress or coercion, either express or implied." State v. Bons, 2007 WI App 124, ¶ 17, 301 Wis. 2d 227, 731 N.W.2d 367 (quoting Phillips, 218 Wis. 2d at 196). Relevant considerations include:
[W]hether any misrepresentation, deception or trickery was used to persuade the defendant to consent; whether the defendant was threatened or physically intimidated; the conditions at the time the search was made; the defendant's response to the officer's request; the defendant's physical and emotional condition and prior experience with police; and whether the officers informed the individual that consent could be withheld.
Bons, 301 Wis. 2d 227, ¶ 17.
¶ 31. Mr. Floyd argued his "consent" was not valid because the circumstances demonstrate it was not voluntarily given. Specifically, he argued that because Deputy Ruffalo had not returned his identification card prior to asking whether he would consent to a search, his response could not be voluntary because he was unlawfully seized. He said "the record shows that Floyd's consent was not voluntary, where in the absence of any suspicion, the deputy withheld [his] documents to prevent the stop from terminating in order to procure [his] agreement to the pat-down." It is true that these facts can be useful in determining the voluntariness of someone's consent. But it is useful to a part of the analysis we have already resolved against Mr. Floyd's position. If an officer withholds a person's documents, there is good reason to believe the person was not "free to leave" at that time. That, in turn, helps us decide whether the person was seized. See, e.g., [418]*418State v. Hogan, 2015 WI 76, ¶ 63, 364 Wis. 2d 167, 868 N.W.2d 124 ("a traffic stop ends when a reasonable person, under the totality of the circumstances, would feel free to leave."). If the seizure is unlawful, the consent is invalid. See, e.g., State v. Jones, 2005 WI App 26, ¶ 9, 278 Wis. 2d 774, 693 N.W.2d 104 ("a search authorized by consent is wholly valid unless that consent is given while an individual is illegally seized." (citing State v. Williams, 2002 WI 94, ¶¶ 19-20, 255 Wis. 2d 1, 646 N.W.2d 834)); see also United States v. Jerez, 108 F.3d 684, 694-96 (7th Cir. 1997). Here, however, we have concluded the traffic stop was not extended and that Mr. Floyd was seized —lawfully—when Deputy Ruffalo requested his consent to the search.7
¶ 32. Requesting permission to search a person who has been lawfully seized does not invalidate the person's consent. See Schneckloth, 412 U.S. at 248-49 (consent given while seized pursuant to a traffic stop was constitutionally valid); United States v. Watson, 423 U.S. 411, 424 (1976) ("[T]he fact of custody alone has never been enough in itself to demonstrate a coerced confession or consent to search."). The routine act of retaining an identification card or driver's li[419]*419cense during a traffic stop, without more, is insufficient evidence of the type of duress or coercion capable of making consent something less than voluntary. If it were otherwise, it would be virtually impossible to obtain consent to a search during a traffic stop. We see no authority to support such a proposition, and Mr. Floyd offers none. So retaining the identification card presented no structural impediment to Deputy Ruffa-lo's request for permission to perform a search; we continue with the inquiry into the voluntariness of Mr. Floyd's response.
¶ 33. The record does not indicate Deputy Ruf-falo employed any misrepresentation, deception, or trickery in seeking Mr. Floyd's consent. There is likewise nothing in the record suggesting Deputy Ruffalo used any threats or physical intimidation of any type in seeking Mr. Floyd's consent. Deputy Ruffalo was the only officer conducting the search, there is no indication Mr. Floyd was handcuffed or that Deputy Ruffalo threatened to use them, there is no suggestion Deputy Ruffalo drew his weapon, and the traffic stop and search occurred during daylight hours with pedestrian and vehicular traffic nearby. As to the remaining factors we are to consider, there is no evidence regarding Mr. Floyd's physical or emotional condition at the time. Similarly, there is nothing in the record indicating Deputy Ruffalo informed Mr. Floyd he could withhold consent, but this factor is not sufficient, in and of itself, to question the voluntariness of Mr. Floyd's consent.8
¶ 34. Under the totality of these circumstances, we conclude the search was constitutionally sound because Mr. Floyd freely and voluntarily consented to it. [420]*420Deputy Ruffalo discovered the illegal drugs while conducting a lawful search, so there was no reason to suppress that evidence. Because we conclude Deputy Ruffalo did not extend the traffic stop, we do not address the State's alternative argument that Deputy Ruffalo had reasonable suspicion of illegal drug activity sufficient to support an extension.9
C. Ineffective Assistance of Counsel
¶ 35. Mr. Floyd claims he received ineffective assistance of counsel because his trial counsel failed to call Officer White (the "cover" officer) as a witness at the suppression hearing. According to Mr. Floyd, Officer White's testimony would have revealed that Deputy Ruffalo did not ask Mr. Floyd for his consent to the search, but rather that he advised Mr. Floyd he was going to perform the search, thus rendering any consent involuntary. See Johnson, 299 Wis. 2d 675, ¶ 16 ("Acquiescence to an unlawful assertion of police authority is not equivalent to consent." (quoting State v. Wilson, 229 Wis. 2d 256, 269, 600 N.W.2d 14 (Ct. App. 1999))).
¶ 36. The Sixth Amendment10 guarantees to a criminal defendant "the effective assistance of coun[421]*421sel." Strickland v. Washington, 466 U.S. 668, 686 (1984). We apply the two-prong Strickland test when assessing a claimed violation of that right. See, e.g., State v. Maday, 2017 WI 28, ¶ 54, 374 Wis. 2d 164, 892 N.W.2d 611. A successful attack on counsel's performance requires that the defendant establish both that trial counsel performed deficiently and that the deficiency was prejudicial. See State v. Pitsch, 124 Wis. 2d 628, 633, 369 N.W.2d 711 (1985); see also Strickland, 466 U.S. at 697.
¶ 37. The first prong requires us to compare counsel's performance to the "wide range of professionally competent assistance." Strickland, 466 U.S. at 690. Only if his conduct falls outside that objectively reasonable range will we find deficient performance. State v. Thiel, 2003 WI 111, ¶ 19, 264 Wis. 2d 571, 665 N.W.2d 305. To show prejudice (the second prong), a defendant must establish "a reasonable probability that, but for counsel's unprofessional errors, the result of the proceeding would have been different." Pitsch, 124 Wis. 2d at 642 (quoting Strickland, 466 U.S. at 694). If the defendant fails to prove one element, it is unnecessary to address the other. Strickland, 466 U.S. at 697.
f 38. Although trial counsel did not have Officer White testify at the suppression hearing, he did offer the essence of his story in his brief. Counsel juxtaposed Deputy Ruffalo's report that he asked Mr. Floyd if he would allow a search with Officer White's report that Mr. Floyd was told he would be searched:
Deputy Ruffalo indicates he asked Mr. Floyd whether he had any weapons and if he could search Mr. Floyd for his (Deputy Ruffalo's) safety. Deputy Ruffalo indicates that Mr. Floyd stated, "yeah, go ahead." City of Racine Police Officer White (the cover officer) reports [422]*422something slightly different in regards to the search. Officer White reports that after having Mr. Floyd exit the vehicle, Deputy Ruffalo told Mr. Floyd that before he could explain the citations he was going to pat down Mr. Floyd for weapons. Officer White indicates that after being told he was going to be searched, Mr. Floyd stated something similar to "go ahead."
The circuit court was not persuaded, instead finding as a factual matter that Deputy Ruffalo asked for Mr. Floyd's consent, and that Mr. Floyd consented.
¶ 39. At the postconviction hearing, Officer White reprised the contents of his report and offered some related commentary. He testified that, after arriving on the scene, he accompanied Deputy Ruffalo to Mr. Floyd's vehicle where Deputy Ruffalo asked Mr. Floyd to step outside. He then explained that "[Deputy] Ruffalo, he — he asked him if he could do an external pat down for weapons and which he consented." When asked whether this was consistent with the report's indication that Mr. Floyd had been "advised"11 he would be searched, Officer White responded that Deputy Ruffalo "said he was going to pat him — asked him to pat him down for weapons .... He asked him for the most part." He could not, however, remember the specific words Deputy Ruffalo used, explaining that a cover officer "can't always hear what's exactly going on between the officer and who they are making contact with" because the cover officer generally "kind [423]*423of watchfes] who's driving the vehicle, you watch the passengers inside the vehicle." When asked whether he recalled Mr. Floyd's response to Deputy Ruffalo, he testified it was his recollection that Mr. Floyd said something along the lines of "go ahead."
¶ 40. Trial counsel also testified at the postcon-viction hearing. He said he included information about Officer White's incident report in the suppression motion but ultimately chose not to call him as a witness because he was "happy as far as how the evidence came out from the deputy, from Deputy Ruffalo, and that he did not have a basis to continue his stop of Mr. Floyd." He was concerned Officer White's testimony would "potentially giv[e] additional information that potentially damaged where I thought I was." Counsel further explained he thought he was "doing pretty well" in terms of arguing Mr. Floyd could not voluntarily consent because he was illegally seized at the time Deputy Ruffalo requested consent. Although counsel could not recall whether he discussed the ultimate decision not to call Officer White with Mr. Floyd, he indicated it would have been his normal practice to do so.
¶ 41. At the conclusion of the hearing, the circuit court acknowledged "some dichotomy from [Officer] White's [incident] report... as to what it meant" in terms of Deputy Ruffalo's exchange with Mr. Floyd, but concluded that trial counsel's decision not to call Officer White was "his tactical approach; it was a reasonable approach . . . ." The circuit court also acknowledged that "[w]e know now after Mr. White testified that whatever [trial counsel] thought, [Officer] White would have corroborated [Deputy] Ruffalo's version to that extent."
[424]*424f 42. Trial counsel's performance was not deficient. It was the State's burden to prove Mr. Floyd freely and voluntarily consented to a search. We recognize that Officer White's report created a potential ambiguity with Deputy Ruffalo's testimony, something Mr. Floyd's counsel ably (albeit unsuccessfully) exploited. And calling Officer White to the stand may have removed the potential ambiguity—but this was a task for the State, if anyone. Mr. Floyd's counsel is not responsible for clarifying the State's evidence.12 Indeed, had he done so, Mr. Floyd might now be arguing his counsel was deficient because he helped the State defeat his motion to suppress. We agree with the circuit court that trial counsel's decision not to call Officer White was a valid tactical choice and did not fall outside "the wide range of professionally competent assistance." See, e.g., State v. Felton, 110 Wis. 2d 485, 502, 329 N.W.2d 161 (1983) (explaining that where "tactical or strategic decisions" are "based upon rationality founded on the facts and the law[,]" counsel will not be deemed to have provided ineffective assistance of counsel). Therefore, Mr. Floyd did not suffer ineffective assistance of counsel.
IV. CONCLUSION
¶ 43. Deputy Ruffalo did not extend Mr. Floyd's traffic stop because the request to perform a search of [425]*425his person was part of the stop's mission. Mr. Floyd was lawfully seized at the time of the request, and he provided his consent to the search freely and voluntarily. This constitutionally-valid search revealed illegal drugs in Mr. Floyd's possession, so the circuit court properly denied his motion to suppress. And because Mr. Floyd's trial counsel did not perform deficiently with respect to Officer White's testimony, Mr. Floyd did not receive ineffective assistance of counsel. Accordingly, we affirm the court of appeals.
By the Court.—The decision of the court of appeals is affirmed.