During a canine search of Appellant-Defendant John Cervine’s vehicle, conducted after a stop for a traffic violation, Missouri Highway Patrol troopers discovered marijuana and methamphetamine. Mr. Cervine pleaded guilty to one count of conspiring to manufacture and distribute a controlled substance, in violation of 21 U.S.C. § 846 and 18 U.S.C. § 2, and one count of possessing, with the intent to distribute, approximately 53.2 grams of methamphetamine, in violation of 21 U.S.C. § 841(a)(1) and 18 U.S.C. § 2. In his plea agreement, Mr. Cervine reserved the right to appeal the district court’s ruling on his motion to suppress the evidence obtained from the traffic stop of his truck and from his subsequent questioning. The district court denied the motion, finding that the troopers’ conduct did not violate the Fourth Amendment. We exercise jurisdiction pursuant to 28 U.S.C. § 1291 and AFFIRM.
I. Background
Missouri state troopers arrested John Cervine on March 11, 2000, during his return trip home to Kentucky from Baxter Springs, Kansas. Mr. Cervine originally traveled to Baxter Springs to visit Timothy Cline, an Oklahoma resident and owner of Biker’s Dream, a motorcycle sales and repair shop in Baxter Springs. DEA agents had been investigating Timothy Cline as a possible methamphetamine distributor and pseudoephedrine supplier since late 1999. Based on information derived from their investigation, including wiretaps of telephone calls on March 7-11, 2001, DEA agents had reason to believe that Mr. Cer-vine was involved with Mr. Cline in trafficking illegal drugs.
On March 11, 2000, Mr. Cervine telephoned Timothy Cline upon arriving in the Baxter Springs area. After first meeting Mr. Cline at his Oklahoma home, Mr. Cer-vine drove to Baxter Springs, arriving at Biker’s Dream at approximately 1:00 p.m. After about five hours, Mr. Cervine left the shop in his truck, with his motorcycle in tow, apparently en route to Kentucky.
DEA agents followed Mr. Cervine from Baxter Springs into Missouri and observed him on two occasions drive at a slow speed through two rest areas without stopping, *868 returning directly to the interstate. The DEA agents testified that narcotics traffickers commonly adopt such behavior as a counter-surveillance technique.
After observing this behavior, the DEA agents contacted the Missouri Highway Patrol, informing them that Mr. Cervine was likely transporting illegal drugs. The DEA agents also requested that the Highway Patrol stop the vehicle for any observed traffic violations and seek permission from Mr. Cervine to search the vehicle. After locating Mr. Cervine’s vehicle, Highway Patrol troopers Scott Mease and Cort Stuart observed his truck veer over the line separating the left passing lane from the right driving lane for approximately two seconds before returning fully to the right lane. The Highway Patrol officers stopped Mr. Cervine for this violation. Mr. Cervine did not deny committing the violation, claiming that deficient tongue weight in his towed trailer caused the vehicle to swerve.
After approaching the truck and informing Mr. Cervine of the basis for the stop, Highway Patrol Trooper Mease requested his driver’s license. Upon receiving this license, Trooper Mease asked Mr. Cervine to accompany him to his patrol car. Mr. Cervine complied. After denying that he was transporting illegal drugs in his vehicle, Mr. Cervine gave the troopers permission to search his truck.
Instead of searching the vehicle themselves, the troopers called in the canine unit to perform the search. Although Mr. Cervine claims that the canine unit did not arrive for approximately three hours, the troopers claim that it arrived within thirty minutes.
A few minutes after arriving, the dog alerted the troopers to the truck’s console, where they located marijuana and methamphetamine in vacuum-sealed packages. Trooper Mease then arrested Mr. Cervine and read him his Miranda rights. Once at Troop D headquarters, Mr. Cervine answered questions posed to him by Missouri Highway Patrol officers.
II. Discussion
A. Standard of Review
In reviewing the denial of a motion to suppress evidence, we accept the factual findings of the district court, and its determination of witness credibility, unless they are clearly erroneous.
See United States v. Flores,
B. Overview of Applicable Fourth Amendment Law
In reviewing the constitutionality of traffic stops under the Fourth Amendment, we conduct a two-step inquiry. First, we must determine “whether the officer’s action was justified at its inception.”
United States v. Gonzalez-Lerma,
C. Reasonableness of the Traffic Stop at Its Inception
“[A] detaining officer must have an objectively reasonable articulable suspicion that a traffic violation has occurred or is occurring before stopping [an] automobile.”
United States v. Soto,
All vehicles in motion upon a highway having two or more lanes of traffic proceeding in the same direction shall be driven in the right-hand lane except when overtaking and passing another vehicle or when preparing to make a proper left turn or when otherwise directed by traffic markings, signs or signals.
Mr. Cervine counters that the troopers did not have probable cause 2 because “crossing over the lane divider for two seconds cannot objectively constitute a violation” of Mo.Rev.Stat. § 304.015.6. 3 We disagree.
To support his argument, Mr. Cervine points to our holding in
United States v. Gregory,
Mr. Cervine misreads our decision in
Gregory.
For purposes of establishing reasonable suspicion, we only consider vehicle and weather conditions when the underlying state statute so directs. We considered these conditions in
Gregory
because the underlying Utah statute contained an-as-nearly-as-practical requirement. The relevant statute in
Gregory,
Utah Code Ann. § 41-6-61(1), requires that “[a] vehicle shall be operated
as nearly as practical
entirely within a single lane.... ”
Id.
(emphasis added). Given the difficult weather, vehicle, and road conditions, it was not “practical” for the driver in
Gregory
to avoid the emergency lane at all times.
See Gregory,
In contrast to the Utah statute, Mo.Rev. Stat. § 304.015.6 does not allow drivers to comply with the right-lane requirement “as nearly as practicable.” Instead, the Missouri statute sets forth only three conditions under which vehicles may enter the left-hand lane: (1) “when overtaking and passing another vehicle”; (2) “when preparing to make a proper left turn”; and (3) “when otherwise directed by traffic markings, signs, or signals.” 4 Id. Unlike Utah Code Ann. § 41-6-61(1), a driver violates Mo.Rev.Stat. § 304.015.6 if his vehicle enters the left-hand lane for any reason other than the three justifications enumerated in the statute. The Missouri statute does not include an exception for improper vehicle weight, driver visibility, or wind. Thus, regardless of the wind, the darkness, or the weight of his trailer, when Mr. Cervine’s truck entered the left lane, he violated Mo.Rev.Stat. § 304.015.6. 5
This violation provided the troopers with reasonable suspicion to stop Mr. Cervine’s car. The fact that the troopers had other motivations for stopping Mr. Cervine has no bearing upon this review. “Subjective intentions play no role in ordinary, probable-cause Fourth Amendment analysis.”
Whren v. United States,
D. Reasonable Suspicion of Illegal Activity as the Basis for the Canine Search
“Generally, an investigative detention must ‘last no longer than is neces
*871
sary to effectuate the purpose of the stop.’ ”
United States v. Patten,
Generally, “[i]f the driver produces a valid license and proof of right to operate the vehicle, the officer must allow him to continue on his way without delay for further questioning.”
Soto,
The district court found that Mr. Cervine did not validly consent to the search of his vehicle and the related detention because the troopers did not return his driver’s license to him prior to obtaining consent.
See Cervine,
In the present case, it is uncontroverted that the initial traffic stop itself did not provide reasonable suspicion for the further detention and search of Mr. Cervine’s vehicle. In determining reasonable suspicion, however, we must also “look to the knowledge of all the police involved in this criminal investigation, since probable cause can rest upon the collective knowledge of the police, rather than solely on that of the officer who actually makes the arrest.”
United States v. Merritt,
Although
Merritt
and
Swingler
apply the collective knowledge doctrine to only an investigative stop and an arrest, respectively, the reasoning of these cases, as well as rulings from outside this circuit, sup
*872
port application of this doctrine to justify a continued detention.
See United States v. Celio,
Following the guidance of
Merritt
and
Swingler,
the district court found that the troopers had reasonable suspicion based both on the representations by DEA Agent Robert Ryan that Mr. Cervine was likely transporting illegal narcotics and on the facts supporting this assertion.
See Cervine,
(1) Timothy Cline was a primary supplier of pseudoephedrine to the primary methamphetamine manufacturer in the state of Kansas and received methamphetamine and other drugs in return for redistribution and use; (2) Cline was a member and former president of the Quapaw, Oklahoma chapter of The Loners motorcycle club and Cervine was the president of The Loners motorcycle club in Kentucky; (3) outlaw motorcycle groups were known to be associated with the drug business; (4) Cervine had been arrested in 1976 for possession of a controlled substance, possession of a hand grenade and possession of a firearm; (5) Cline and Cervine had recently been seen talking with each other at the national officers’ meeting of The Loners motorcycle club in Las Vegas, Nevada; (6) authorized wiretaps of Cline’s residential telephone on March 7, 2000 and March 11, 2000 revealed that Cline and Cervine were friends or close associates, that Cline called Cervine “Chief,” and Cervine called Cline “Pony,” that Cer-vine was planning to come to Kansas or Oklahoma and to bring his motorcycle to Cline’s shop for repairs; (7) Rudolph James Maio, another friend or associate of Cline’s, had been stopped in Oklahoma on February 22, 2000, after leaving Cline’s motorcycle shop; Troopers found approximately $84,000, some of which was wrapped in a heat-sealed bag, in the saddlebags of the motorcycle Maio was hauling, and immediately detected the odor of marijuana upon opening that wrapper; (8) Cervine drove from Kentucky to Kansas, stayed approximately five hours at Cline’s shop, then returned to his vehicle and drove toward Kentucky; (9) Cervine pulled off the interstate at least twice into a rest stop or exit and drove around very slowly but did not stop. Id.
Mr. Cervine does not dispute these facts. 8 Given these facts and the experience of DEA Agent Ryan, the troopers possessed reasonable, articulable suspicion of criminal activity sufficient to justify detaining Mr. Cervine for 30-50 minutes.
That these facts could also reflect innocent conduct, as Mr. Cervine alleges, is of no consequence. “A determination that reasonable suspicion exists ... need not rule out the possibility of innocent conduct.”
Arvizu,
Finally, the length of Mr. Cervine’s detention did not violate the Fourth Amendment. Based on the troopers’ testimonies and the dispatch log records, the district court concluded that the traffic stop, detention, and canine search of Mr. Cervine’s
*873
vehicle lasted approximately fifty minutes.
Cervine,
III. Conclusion
Considering the totality of the circumstances, we AFFIRM the district court’s denial of Cervine’s motion to suppress.
Notes
. Mr. Cervine uses the terms "probable cause” and “reasonable suspicion” interchangeably throughout his brief. However, our case law makes clear that “[w]hile either probable cause or reasonable suspicion is sufficient to justify a traffic stop, only the lesser requirement of reasonable suspicion is necessary.”
United States v. Callarman,
. Mr. Cervine also argues, without any evi-dentiary support, that Trooper Mease believed that Mr. Cervine violated Mo.Rev.Stat. § 314.015.5(1) and that this alleged violation supplied the actual basis for the traffic stop. Trooper Mease testified, however, that Mr. Cervine's apparent violation of Mo.Rev.Stat. § 304.015.6 formed the basis of his traffic stop. Mr. Cervine provided no contrary evidence. The district court accepted the testimony of Trooper Mease.
United States v. Cervine,
. Mr Cervine does not contend that he crossed into the left-hand lane for any of these three recognized conditions.
. The Missouri Court of Appeals in
State v. Mendoza,
.We do not hold that a suspect must commit a traffic violation before officers may stop a vehicle to investigate drag trafficking. Because the government did not argue that the troopers stopped Mr. Cervine based on the objective, reasonable, and articulable suspicion of drag trafficking as communicated to them by the DEA, absent any traffic violation, we had no occasion to consider that argument.
See United States v. Celio,
. Although we can find no opinion that applies the collective knowledge doctrine to justify a search when the stop was based on an unrelated traffic violation, we see no reason that the policies underlying the collective knowledge doctrine would not support such a use.
Cf. United States v. Shareef,
. Mr. Cervine claims that he actually stopped at the rest stops. The district court, however, accepted the contrary testimony of Agent Ryan. We accept the district court’s factual finding on this score.
Flores,
