Mario Alberto Bueno pleaded guilty to possessing with intent to distribute five kilograms or more of powder cocaine. The district court reduced Bueno’s U.S. Sentencing Guidelines offense level and granted a downward departure from the guidelines, resulting in a sentence of eighteen months in prison and three years of supervised release. The government appeals this sentence. Bueno cross-appeals, arguing that the district court erred in denying his motion to suppress and in quashing his subpoena duces tecum. We affirm on Bueno’s cross-appeal, and we vacate the sentence and remand to the district court for resentencing. 1
I.
On January 9, 2001, Corporal Rex Seism and Trooper Kirk Davis (collectively, officers) of the Missouri State Highway Patrol stopped Bueno for a traffic violation. The officers had been traveling westbound on Interstate 70 in their patrol car and met Bueno’s vehicle traveling eastbound on the same highway. Seism testified that he observed that the vehicle did not have a front license plate and proceeded to stop the vehicle. Seism approached the vehicle and advised Bueno that he had been stopped because his vehicle was lacking license plates and because the officers could not observe a temporary vehicle registration affixed to the vehicle. Seism asked Bueno for his license and registration. Bueno handed over his license and pointed to the temporary registration that was affixed to the vehicle’s windshield. The temporary registration stated that the vehicle belonged to someone other than Bueno.
After examining the temporary registration, Seism ordered Bueno to exit his vehi- *1021 ele and wait in the patrol car while the officers checked on the license and temporary registration and until they had completed the traffic stop. While Bueno was waiting in the patrol car, Seism inquired about the owner of the vehicle and Bueno’s destination. Bueno responded that the vehicle belonged to his brother and that he was traveling from California to St. Louis, Missouri, where he would meet his brother and they would purchase some cars to transport back to California.
After the officers completed checking Bueno’s license and registration, they documented the warning that they gave to Bueno, returned his license and registration, and told Bueno to have a safe trip. At that point, Bueno began to exit the patrol car. Seism testified that he then asked Bueno for consent to search his vehicle and that Bueno said “Sure, go ahead.” Davis’s testimony corroborates Seism’s account. Bueno testified that Seism did not ask for consent to search, but instead grabbed Bueno’s arm, put him on the hood of the vehicle, told him that he was going to have to search the vehicle, and that Bueno raised his hand and said “Fine.” Upon searching the vehicle, Seism found a false floor and an access door leading to a compartment that was not standard for such a vehicle. Because this caused him to suspect that Bueno was trafficking contraband, he placed Bueno in handcuffs. Seism then returned to the vehicle and found 76.9 kilograms of cocaine inside the compartment. He then read Bueno his rights and arrested him for drug trafficking.
Bueno pleaded guilty to possessing with intent to distribute five kilograms or more of powder cocaine in violation of 21 U.S.C. §§ 841(a)(1) and (b)(1)(A). Sentencing took place on April 28, 2004. In accordance with the Presentence Investigation Report (PSR), the district court applied the 2002 version of the sentencing guidelines 2 and determined that Bueno’s base offense level was thirty-six and that § 841(b)(1)(A) required a mandatory minimum sentence of ten years in prison. The district court further determined, however, that Bueno qualified for the safety valve reduction pursuant to § 5C1.2 of the guidelines. The district court also concluded that Bueno was entitled to a two-level reduction under § 2Dl.l(b)(6) and a three-level reduction under §§ 3El.l(a) and (b) for acceptance of responsibility. This brought Bueno’s adjusted offense level to thirty-one, which provided for a sentencing range of 108 to 135 months.
Bueno then argued that he was entitled to a minimal participant reduction under § 3B1.2. To buttress his claim that other participants were also involved in the offense, Bueno offered evidence that the vehicle’s temporary registration was in another’s name, that personal papers of another were found in the vehicle, and that Bueno possessed driving directions to Chicago that were in another’s handwriting. Bueno also explained that Carlos, a man whom he had asked for a loan, gave him the job of driving the vehicle and that another participant met him at the airport to provide him with the vehicle. Bueno further explained that he did not fully cooperate with the police in identifying Carlos because he was afraid that Carlos would retaliate against him.
Over the government’s objections, the district court granted Bueno’s request for a minimal participant reduction. This lowered Bueno’s offense level to thirty under § 2D1.1. Taking into account the two-level reduction under § 2D1.1(b)(6), the three-level reduction for acceptance of responsibility, and the four-level reduction for min *1022 imal participation, the district court determined Bueno’s total offense level to be twenty-one. This corresponded to a sentencing range of thirty-seven to forty-six months.
Finally, Bueno argued that he was entitled to a downward departure for aberrant behavior under § 5K2.20 and family ties and responsibilities under § 5H1.6, as well as a general departure under § 5K2.0. Bueno argued that a departure was warranted because this was his first offense, he was under great financial pressure when he committed the offense, his wife was suffering from lupus and rheumatoid arthritis, and because, in his view, this was a case of exceptional circumstances. The district court granted a downward departure for the reasons stated by Bueno and, as set forth above, sentenced Bueno to eighteen months in prison and three years of supervised release. This constituted a fifty-one percent departure from the bottom of the guidelines range for an offense level of twenty-one and an eighty-three percent departure from the bottom of the guidelines range for an offense level of thirty-one.
II.
In
United, States v. Booker,
the Supreme Court struck the statutory provisions that made sentencing within the U.S. Sentencing Guidelines mandatory.
A.
The government argues that the district court erred in determining that Bueno was entitled to a downward adjustment as a minimal participant under § 3B1.2 of the guidelines. We review the district court’s determination for clear error.
See United States v. Denton,
Section 3B1.2 provides that a defendant’s role in an offense may be reduced by four levels if the offense involved multiple participants and the defendant was substantially less culpable than the average participant. U.S.S.G. § 3B1.2, cmt. nn. 2 & 3. “The propriety of a downward adjustment is determined by comparing the acts of each participant in relation to the relevant conduct for which the participant is held accountable and by measuring each participant’s individual acts and relative culpability against the elements of the offense.”
Ramos-Torres,
Bueno offered no evidence of the relative culpabilities of other participants in the offense and therefore did not carry his burden of proving that he was eligible for the reduction. Accordingly, the district court’s determination that Bueno was entitled to a downward adjustment because of his minimal participation in the offense is *1023 not supported by substantial evidence and was clearly erroneous.
B.
We review for abuse of discretion a district court’s decision to grant a downward departure from the appropriate guidelines range.
United States v. Porter,
To be entitled for a downward departure due to aberrant behavior under § 5K2.20, the offense must have been a single criminal occurrence or transaction that was committed without significant planning, was of limited duration, and represented a marked deviation by the defendant from an otherwise law-abiding life. U.S.S.G. § 5K2.20, cmt. n. 1. The offense must have been more than something out of the defendant’s character; it must have been a spontaneous and thoughtless act.
United States v. Weise,
Family ties and responsibilities may also be a ground for departure when extraordinary circumstances are present such that the case lies outside the heartland of cases covered by the guidelines.
See
U.S.S.G. § 5H1.6; U.S.S.G. § 5K2.0;
see also United States v. Tobacco,
A district court may also grant a general downward departure pursuant to § 5K2.0 if it determines that a mitigating circumstance, either in kind or to a degree, was not adequately taken into consideration by the Sentencing Commission in formulating the guidelines and the case falls outside the heartland of cases covered by the guidelines. We see nothing in the circumstances that would justify a finding that this case is other than the all too common situation in which a defendant agrees to transport drugs for cash.
C.
Finally, we review the district court’s imposition of an eighteen-month sentence for reasonableness.
See, e.g., United States v. Hadash,
In the present case, the circumstances are not so extraordinary that they warrant an eighty-three percent departure from an offense level of thirty-one. An eighteen-month sentence does not adequately reflect the seriousness of Bueno’s offense, afford adequate deterrence, or adequately avoid sentencing disparities among similarly situated defendants. Accordingly, we conclude that the district court abused its discretion in granting' such a large departure and that the sentence imposed is unreasonable.
III.
In his cross-appeal, Bueno contends that the district court erred in denying his motion to suppress. We examine the factual findings underlying the district court’s decision for clear error and review
de novo
the ultimate question of whether the Fourth Amendment has been violated.
United States v. Carter,
First, and underlying each of his Fourth Amendment arguments, Bueno contends that the district court clearly erred in finding that the officers were credible witnesses. We generally defer to the district court on issues of credibility, however, because the district court is in the best position to assess the credibility of witnesses.
See United States v. Walsh,
Bueno next argues that because there was no reasonable suspicion for the traffic stop, all evidence arising out of the stop should be suppressed as fruit of the poisonous tree. He contends that the stop was based on a mistake of law and therefore did not provide the requisite reasonable suspicion for the stop. We have held, however, that neither mistake of law nor mistake of fact renders a traffic stop illegal so long as the officer’s actions were objectively reasonable in the circumstances.
United States v. Smart,
Bueno also argues that the officers illegally ordered him out of his vehicle. Once a vehicle has been stopped for a traffic violation, a police officer may order the driver out of the vehicle without violating the Fourth Amendment,
Pennsylvania v. Mimms,
Likewise, no Fourth Amendment violation occurred when the officers required Bueno to remain in the patrol car during the stop. Once officers legitimately stop a vehicle, they are entitled to conduct an investigation that is reasonably related in scope to the circumstances that initially justified the stop.
United States v. Bloomfield,
Bueno further argues that the district court erred in determining that he voluntarily consented to the search of his vehicle. As recounted above, Seism testified that he asked Bueno for permission to search his vehicle and that Bueno responded by stating “Sure, go ahead.” Davis testified to the same effect. We conclude that the record supports the district court’s finding that Bueno consented to the search. Bueno also argues that his limited ability to speak and understand English and his limited experience with police officers made any consent that he may have given involuntary. Consent is voluntary if it is “an essentially free and unconstrained choice by its maker.”
Schneckloth v. Bustamante,
IV.
Finally, Bueno argues that he was deprived of a fair hearing because the district court erroneously quashed his subpoena duces tecum. Bueno also argues that he was denied a fair hearing because the court failed to order Seism to explain why he refuses to use a tape recorder or forms to record defendants’ consents. Bueno fails to cite any law supporting *1026 either of these claims, and we dismiss the latter as meritless.
We review for abuse of discretion the district court’s decision to quash a subpoena.
United States v. Hardy,
The district court’s judgment imposing a sentence of eighteen months in prison and three years of supervised release is vacated, and the case is remanded for resen-tencing in accordance with the opinion in
Booker,
