Orlando Fiala was convicted in district court of conspiracy to distribute and possession of marijuana. His co-defendant John DeLuna was convicted of conspiracy to distribute marijuana and of being a felon in possession of a firearm. Both appeal the district court’s denial of their motions to suppress evidence discovered by police in an аutomobile driven by Fiala and owned by DeLuna that was searched after a traffic stop. Fiala also appeals his sentence, contesting Sentencing Guidelines offense level enhancements levied by the district court for obstruction of justice and possession of a weapon during the commission of a drug offense. We affirm both the district court’s denial of the suppression motion and the imposition of the drug offense weapons enhancement, but reverse the imposition of the obstruction of justice enhancement.
I.
On the morning of December 29, 1987, Illinois State Trooper Michael Ores observed a yellow Ford driven by defendant Fiala on Interstate 55 in Central Illinois. The Ford piqued Ores' interest because it appeared to be heavily loaded, with its tail end riding low. Ores radioed Illinois State Trooper Greg Neumann who was nearby in another car, and the two began to follow Fiala’s vehicle. Soon thereafter, the troopers observed the Ford drift roughly one-half its width over the “fog line” on the right side of the highway for 5-10 seconds before returning to its proper place in the driving lane.
The trooрers stopped Fiala for violating § 11-709 of the Illinois Vehicle Code (“whenever any roadway has been divided into two or more clearly marked lanes for traffic ... [a] vehicle shall be driven as nearly as practicable within a single lane and shall not be moved from such lane until the driver has first ascertained that such movement can be made with safety.”) Ill. Rev.Stat., ch. 9572, § 11-709. Neumаnn approached the car, and asked the driver, Fiala, and his passenger Susan Lucio, for their drivers’ licenses. Lucio gave her license to the trooper, but Fiala replied that he had lost his license at a previous stop for gas. A radio check indicated that Fia-la’s license was suspended but that Lucio’s was valid. The query also revealed that the Fоrd belonged to Reynaldo Segura, though Fiala claimed that the car belonged to his brother Charles. Segura turned out to be an alias of defendant John DeLuna.
Neumann gave Fiala a warning for improper lane usage and a citation for driving without a valid license, the latter being a Class A misdemeanor in Illinois. Ill.Rev. Stat. ch. 9572, § 6-303. He also radioed a request for a criminal histоry check on Fiala and Lucio. The check came back positive — Neumann was informed that Fia-la had previously been arrested for possession of marijuana. In response, the trooper asked Fiala if there was anything illegal in the car. Fiala replied that there was not. Neumann then asked Fiala and Lucio if they would consent to a search оf the car. The two gave their oral consent, but refused to sign written consent forms.
Rather than immediately search the car, Trooper Neumann radioed his superior, Sergeant Gary McConkey, for further instructions. McConkey directed Neumann not to begin his search until a K-9 unit (an officer with a drug-sniffing dog) arrived to examine the car for the scent of narcotics. The troopers waited 172 hours at the roadside with Fiala and Lucio before the dog and his handler arrived. When Kimmo the drug-sniffing dog finally made his appearance, it wasn’t for naught — the canine alerted the troopers to the possible presence of drugs in the trunk and in a box in the backseat of the Ford. On the basis of the dog’s sniff search, Neumann searched *287 the car and found two large bags of marijuana in the box and two handguns in a briefcase in the rear.
Fiala, Lucio, and DeLuna, the owner of the Ford, were indicted for conspiring to distribute marijuana and possession of marijuana. DeLuna was also charged with being a felon in possession of a firearm and carrying a firearm during a drug offense. In a subsequent suppression hearing, the defendants challenged the constitutionality of the troopers’ search of the Ford. They argued that the troopers’ stop of their car was pretextual, that the troopers failed to obtain valid consent for the search, that the IV2 hour wait for the K-9 unit at the roadside constituted an unreasonable seizure, and that the troopers lacked authority to search the closed briefcase in the Ford because Kimmo did not indicate that it might contain drugs.
The district court denied defendants’ suppression motions. Fiala and DeLuna then entered conditional guilty pleas (conditioned on their right to appeal the denial of their suppression motion): Fiala pled guilty to the conspiracy and possession charges and DeLuna pled guilty to the conspiracy and firearm charges. The district court sentenced Fiala to concurrent terms of 96 months for the conspiracy and possession counts, and sentenced DeLuna to concurrent terms of 84 months for the conspiracy count and 60 months for the firearm count.
Fiala and DeLuna now appeal the district court’s denial of their suppression motion. Fiala alsо appeals his sentence.
II.
A. Constitutionality of the Traffic Stop
Defendants’ first argument is that the troopers’ traffic stop of the Ford was a mere pretext to facilitate the search for narcotics.
1
See, e.g., United States v. Lefkowitz,
In
United States v. Trigg,
Applying the Trigg test in this case, we find that the troopers’ stop of Fiala’s car did not violate the fourth amendment. Un *288 der § 11-709 of the Illinois Vehicle Code, the troopers did indeed have cause to stop the Ford for partially swerving off the roadway. The district court found the troopers’ testimony regarding Fiala’s erratic driving сredible, and we defer to that finding. The second prong of the pretext inquiry is easily met as well: under § 16-102 of the Vehicle Code, state troopers are authorized to enforce the Illinois traffic laws as they did in this case. See Ill.Rev.Stat. ch. 95%, § 16-102. We conclude that the stop of Fiala’s car was not pretextual and did not violate the fourth amendment.
B. Constitutionality of the Search
Defendants tender a number of challenges to the troopers’ search of the car. They contend that their consent to the search was deficient, that they were unreasonably seized during the 1% hour roadside wait for the drug-sniffing dog, and that the troopers did not have probable cause to search the closed briefcase in the backseat of the car in the absence of a pоsitive sniff from their trusty mastiff, Kimmo.
The facts here present a variety of grounds on which to affirm the district court’s denial of defendants’ suppression motion. The most straightforward involves the search incident to arrest doctrine.
See New York v. Belton,
Belton,
of course, sanctions only those searches that are incident to full custodial arrests. Trooper Neumann, in this case, was in faсt authorized under Illinois law to arrest Fiala for driving without a valid license.
See People v. Hampton,
It also follows that the 172 hour roadside detention of Fiala while the troopers awaited the arrival of a drug-sniffing dog was nоt unreasonable either. Even if Fiala wasn’t detained at the roadside pending the dog’s arrival, he would have been detained anyway in McLean County Jail as a result of his arrest for driving without a valid license. Fiala’s passenger Lucio may have a better claim in this regard, as she was not lawfully under arrest, but she is not party to this appeal. DeLuna, of course, was not a рassenger in the Ford and so has no claim in this respect either.
III.
Fiala also appeals his sentence. Specifically, he contends that the district court erred by enhancing his offense level by two points for possession of a weapon during the commission of a drug offense, and by another two points for obstruction of justice.
*289 A.
Section 2D1.1(b)(1) of the Sentencing Guidеlines provides for a two point offense level enhancement “[i]f a dangerous weapon (including a firearm) was possessed during the commission of the offense.” Fiala argues that the § 2D1.1(b)(1) enhancement “requires a mental state which is of an intentional, reckless, or criminally negligent nature” and that such scienter has not been proven here: he contends that thе guns at issue were found in a briefcase belonging to defendant DeLuna (a point which the government concedes) and that the government failed to prove that he had any knowledge of the weapons’ existence.
We agree that Fiala should not receive a § 2D1.1(b)(1) enhancement absent a showing that he had knowledge of the weapons in question. At the time Fiаla committed his offense, § 1B1.3 of the Guidelines, which provides general guidance for the application of offense level adjustments, directed sentencing courts to consider awarding enhancements where the harm or risk of particular acts or omissions specified in the adjustment subsections “was caused intentionally, recklessly, or by criminal negligence.” § lB1.3(b). The Fifth Circuit and D.C. Circuit have both read this language to import a scienter requirement into § 2Dl.l(b)(l).
See United States v. Suarez,
In this case, the district court expressly found that Fiala possessed the requisite scienter. After examining evidence which demonstrated that DeLuna and Fiala worked closely with one another in the course of their drug conspiracy, as well as evidence that linked Fiala’s sister and De-Luna’s wife to the weapons in question, the district court found that Fiala himself must have hаd knowledge of the weapons belonging to DeLuna that he was carrying in the Ford. Upon review of the record, we cannot say that this finding was clearly erroneous.
B.
We do, however, find the district court’s second enhancement to be in error. The court gave Fiala a two point offense level enhancement for obstruction of justice under § 3C1.1 of the Sentencing Guidelines. 3 Section 3C1.1 states:
If the defendant willfully impeded or obstructed, or attempted to impede or obstruct the administration of justice during the investigation or prosecution of the instant offense, increase the offense level by 2 levels.
The basis for the enhancement in this case was a statement made by Fiala to trooper Neumann upon being stopped on Interstate 55. Neumann asked Fiala if he had anything illegal in the car, and Fiala responded that he did not. The district court concluded that Fiala should receive a § 3C1.1 obstruction of justice enhancement for uttering his exculpatory statement. We disagree.
Both the government and Fiala have recognized that the validity of the obstruction of justice enhancement turns on our interpretаtion of Application Note 3 of § 3C1.1. Note 3 states that “[t]his provision is not intended to punish a defendant ‘for the exercise of a constitutional right.’ ” It specifies that “[a] defendant’s denial of guilt is not a basis for application of this provision.” Application Note 2 is also relevant to our interpretation of § 3C1.1. It legislates what amounts to a rule of lenity for the purposes of interpreting § 3C1.1: “In applying this provision, suspect testimony and statements should be evaluated in a light most favorable to the defendant.”
*290 The government argues that Note 3’s protection of exculpatory statements from the reach of § 3C1.1 is not applicable here. Fiala’s lie, the government contends, “was not a denial of guilt, since he was not acсused of any crime” at the time that trooper Neumann posed his question. Under the government’s reading, § 3C1.1 would distinguish between those denials of guilt uttered before the initiation of judicial proceedings, and those spoken after such proceedings have begun, and would privilege only the latter. The government has offered no reason for its distinction; the only explanation we can discern is that the government's theory conveniently allows Fiala to receive an additional two point offense level enhancement, whereas a more uniform reading of § 3C1.1 would not.
We find no basis for the government’s distinction in the text of § 3C1.1 or in the accompanying Commentary. Fiala’s statement to Neumann was no more than a denial of guilt, and as such, falls squаrely within Note 3's exception to the obstruction of justice enhancement. The only significant limitation on the denial of guilt exception for which we have found judicial support is the proposition that the exception does not apply to exculpatory statements made under oath.
See, e.g., United States v. Acosta-Cazares,
By contrast, we have found significant support for Fiala’s argument that the enhancement was in error. Amendments to the Guidelines Commentary that became effective shortly after Fiala was sentenced clarify that statements such as Fiala’s are not grounds for the imposition of an enhancement under § 3C1.1. Notе 4 of the amendments to § 3C1.1 explains that “making false statements, not under oath, to law enforcement officers” does not warrant application of a § 3C1.1 enhancement, “unless Application Note 3(g) applies.” Note 3(g) provides that enhancement is appropriate if a defendant made a “materially false statement to a law enforcement officer that significantly obstructed or impeded the official investigation.” Fiala’s statement clearly does not meet the standards of Note 3(g): his denial of guilt was neither material nor could it possibly be said to have significantly obstructed the troopers’ investigation. Under the recent amendments to the Guidelines, then, Fiala’s statement would not warrant an obstruction of justice enhancement. Although the Commentary amendments technically do not apply to Fiala, we believe it proper to consider them in our interpretation of § 3C1.1: the relevant commentary notes were amended merely to clarify the text of § 3C1.1 (which was not itself amended), and we see no reason to ignore such help from the Sentencing Commission in our attеmpt to give meaning to the less substantive pre-1990 § 3C1.1 commentary.
See United States v. Aguilera-Zapata,
We conclude that Fiala should not have been given an obstruction of justice enhancement.
Accord United States v. Martin,
IV.
For the foregoing reasons, we affirm the district court’s denial of the defendants’ suppression motion and remand for resen-tencing consistent with this opinion.
Notes
. We note that only Fiala may properly challenge the constitutionality of thе traffic stop. The district court found that DeLuna, as owner of the Ford, had standing to challenge the troopers’ search of the vehicle, but did not confer standing on DeLuna to challenge the stop, a distinct fourth amendment intrusion.
. We recently reexamined and reaffirmed our pretextual search analysis in a second appeal in the
Trigg
case.
See United States v. Trigg,
. The Sentencing Guidelines were amended in November 1990, eight months after Fiala was sentenced. Unless otherwise specified, our references are to the old version of § 3C1.1 under which Fiala received his enhancement.
