Odor of Marijuana and Flight Establish Probable Cause to Search a Vehicle’s Trunk; Within-Guidelines Sentences Need Not “Robotically Tick Through” § 3553(a)

Introduction

In United States v. Melvin Maxwell (4th Cir. June 9, 2026) (unpublished), the Fourth Circuit affirmed the denial of a motion to suppress evidence recovered from a vehicle search and also affirmed the procedural reasonableness of a within-Guidelines sentence that included supervised release. The appeal arose from a traffic stop in South Carolina that escalated after the officer reported a strong odor of marijuana and the driver fled.

The key issues were: (1) whether the initial traffic stop was supported by a valid observed violation (a left-lane “slow driving”/passing-lane restriction under South Carolina law); (2) whether officers had probable cause to search the vehicle’s trunk based on the odor of marijuana and the defendant’s flight; and (3) whether the sentencing court adequately explained its consideration of the 18 U.S.C. § 3553(a) factors and its rejection of a request for no supervised release.

The parties were the United States (Appellee) and Melvin Antonio Eugene Maxwell (Appellant), who entered a conditional guilty plea preserving his suppression challenge.

Summary of the Opinion

  • Traffic stop: The Fourth Circuit held the district court did not clearly err in finding the officer credibly observed a left-lane violation under S.C. Code § 56-5-1885(A), making the stop lawful.
  • Trunk search: The court held probable cause supported the vehicle search; it emphasized that the “odor of marijuana alone” can establish probable cause and noted the defendant’s flight further supported probable cause under the totality of circumstances.
  • Sentence: The court held the sentence was procedurally reasonable; the district court was not required to “robotically tick through” each § 3553(a) factor (especially for a within-Guidelines sentence) and sufficiently explained its rejection of Maxwell’s request to avoid supervised release.

Analysis

Precedents Cited

The panel’s reasoning leaned heavily on established Fourth Circuit and Supreme Court doctrine governing traffic stops, vehicle searches, and sentencing explanations:

United States v. Pulley, 987 F.3d 370 (4th Cir. 2021)

The court used United States v. Pulley for the appellate standard of review on suppression rulings: legal conclusions are reviewed de novo, factual findings for clear error, and the evidence is viewed in the light most favorable to the Government. That framing mattered because Maxwell’s challenge turned largely on factual disputes and credibility (i.e., whether the left-lane violation actually occurred).

United States v. Palmer, 820 F.3d 640 (4th Cir. 2016)

United States v. Palmer supplied the principle of substantial appellate deference to district court credibility determinations at suppression hearings. The Fourth Circuit invoked it to decline reweighing the officer’s testimony and body-worn-camera evidence, thereby sustaining the district court’s finding that a traffic violation occurred.

United States v. Branch, 537 F.3d 328 (4th Cir. 2008)

United States v. Branch supported the foundational rule that observing a traffic violation provides sufficient justification to detain the vehicle for the “traditional incidents” of a traffic stop. Once the left-lane violation was accepted as fact, Branch effectively foreclosed the claim that the initial seizure was unlawful.

United States v. Scheetz, 293 F.3d 175 (4th Cir. 2002)

The trunk-search question was anchored by United States v. Scheetz, which the panel quoted for the rule that “the odor of marijuana alone can satisfy the probable cause requirement to search a vehicle or baggage.” This case thus reinforces that, in the Fourth Circuit, marijuana odor—without more—can justify a vehicle search under the automobile exception, absent intervening doctrinal change or materially different facts.

District of Columbia v. Wesby, 583 U.S. 48 (2018)

The court cited District of Columbia v. Wesby for the totality-of-the-circumstances approach and the proposition that “unprovoked flight upon noticing the police” is “suggestive of wrongdoing” and may be treated as suspicious behavior. In this case, flight did not substitute for the odor-based probable cause, but it strengthened it—particularly as the search extended to the trunk and the officer had additional reason to suspect contraband.

States v. Patterson, 25 F.4th 123 (2d Cir. 2022)

The panel also cited States v. Patterson from the Second Circuit to illustrate that considering flight as a factor supporting probable cause to search a vehicle is a recognized approach in other circuits. While not binding, it was used to confirm that the inference drawn from flight is mainstream and compatible with Fourth Amendment “totality” analysis.

United States v. Friend, 2 F.4th 369 (4th Cir. 2021) and Gall v. United States, 552 U.S. 38 (2007)

On sentencing procedure, the court relied on United States v. Friend and Gall v. United States for the abuse-of-discretion standard and the catalog of “significant procedural error” (e.g., miscalculating Guidelines, treating them as mandatory, failing to consider § 3553(a), or failing to explain the sentence).

United States v. Freitekh, 114 F.4th 292 (4th Cir. 2024)

United States v. Freitekh supplied the key articulation that district courts need not “robotically tick through” every § 3553(a) factor—especially where the sentence is within the properly calculated Guidelines range. The panel used that principle to uphold a relatively concise explanation, supplemented by record statements focusing on Maxwell’s criminal history and recidivism.

Legal Reasoning

1) The stop: traffic violation + deference to factfinding

The legality of the stop turned on whether Maxwell violated South Carolina’s left-lane restriction, S.C. Code § 56-5-1885(A). The district court characterized the dispute as a “credibility issue,” credited the officer’s account (supported by body-worn-camera footage), and found a violation occurred. On appeal, the Fourth Circuit treated that as a factual finding reviewed for clear error and emphasized deference to the trial judge’s credibility determinations (United States v. Palmer). With that predicate fact in place, the stop was justified under the settled rule that an observed traffic violation supports a stop and the ordinary tasks incident to it (United States v. Branch).

2) The trunk search: marijuana odor (alone) + flight (additional support)

The court found probable cause to search the vehicle based on two reinforcing facts:

  1. Odor of marijuana: The opinion treated this as uncontested and, citing United States v. Scheetz, reiterated that marijuana odor alone can satisfy probable cause for a vehicle search.
  2. Flight: Maxwell accelerated away during the stop and later fled on foot after crashing. The court treated flight as a relevant suspicious circumstance under District of Columbia v. Wesby, and it cited States v. Patterson to underscore that flight can support probable cause to search a stopped vehicle.

The panel’s bottom line was framed conservatively: “at the very least,” odor plus flight created probable cause to search the trunk for evidence of a crime. This phrasing signals that the court viewed the odor evidence as powerful and flight as confirmatory, not necessary.

3) Sentencing: adequate consideration of § 3553(a) and explanation for denying a variance from supervised release

Maxwell argued the district court’s mention of § 3553(a) was too cursory and that it failed to explain why it imposed supervised release despite his request for none. The Fourth Circuit rejected both claims:

  • § 3553(a) consideration: The district court expressly stated it had considered the § 3553(a) factors and made individualized remarks about Maxwell’s criminal history and continued offending. Under United States v. Freitekh, this sufficed for a within-Guidelines sentence.
  • Variance request (no supervised release): The panel found the court directly addressed Maxwell’s stated concern (potential travel restrictions by probation) and explained its view that probation would be fair if Maxwell followed conditions. That explanation satisfied Gall v. United States/United States v. Friend procedural requirements.

Impact

Although the decision is “UNPUBLISHED” and expressly “not binding precedent,” it is still instructive in three ways:

  1. Reinforcement of odor-based probable cause: The opinion reiterates—without qualification—that marijuana odor alone can establish probable cause to search a vehicle (United States v. Scheetz). In suppression litigation, defendants should expect courts to treat odor testimony as legally significant; the practical battleground will often be credibility and corroboration (e.g., camera footage, consistency of officer reports).
  2. Flight as a compounding factor: By pairing odor with flight, the case illustrates how behaviors during a stop can rapidly strengthen probable cause under a “totality of the circumstances” approach (District of Columbia v. Wesby). It signals that attempted evasion may expand the perceived likelihood of contraband, supporting broader search scope.
  3. Sentencing explanation in within-Guidelines cases: The decision underscores that appellate courts will not require lengthy factor-by-factor recitations where the record shows the court considered § 3553(a) and responded to the defendant’s main arguments—especially when the sentence falls within the Guidelines (United States v. Freitekh).

Complex Concepts Simplified

Motion to suppress
A request to exclude evidence because it was obtained in violation of the Constitution (typically the Fourth Amendment).
Probable cause
A practical, common-sense standard: whether the facts would lead a reasonable officer to believe evidence of a crime will be found in the place searched.
Automobile exception
A Fourth Amendment doctrine allowing warrantless searches of vehicles when officers have probable cause, due to vehicles’ mobility and reduced privacy expectations.
Clear error vs. de novo review
“Clear error” is highly deferential and applies to factual findings; “de novo” means the appellate court decides the legal question anew. In suppression appeals, this division often determines whether the district court’s ruling is likely to be reversed.
Guidelines range
The advisory sentencing range calculated under the U.S. Sentencing Guidelines; courts must calculate it correctly but are not bound to impose a sentence within it.
Procedural reasonableness
Whether the court used the right process (proper Guidelines calculation, consideration of § 3553(a), accurate facts, and adequate explanation), as opposed to whether the sentence was too high or too low (substantive reasonableness).
Variance
A sentence outside the Guidelines range (or a requested departure from a typical component, such as supervised release) based on the statutory factors in § 3553(a).
Supervised release
A term of court supervision after prison with conditions (e.g., reporting, travel rules). Violations can result in revocation and additional imprisonment.

Conclusion

United States v. Melvin Maxwell affirms two practical rules frequently litigated in federal criminal cases: (1) credibility-backed findings of a traffic violation will sustain a stop on appeal, and (2) marijuana odor—especially when combined with flight—supports probable cause to search a vehicle, including the trunk. On sentencing, the case reinforces that within-Guidelines sentences need not be accompanied by an exhaustive § 3553(a) recital, so long as the record reflects consideration of the statutory factors and a meaningful response to the defendant’s principal arguments.