Mission of a Traffic Stop: 

Lawful Prolongation of a Traffic Stop Based Upon Newly Developed Reasonable Suspicion: 

Enforcement of Federal Law by a State Law Enforcement Officer 

Probable Cause to Seize a Vehicle 

Probable Cause to Search a Vehicle

United States v. Steinman (9^th Cir. Mar. 5, 2025) __ F.4^th __ [2025 U.S.App. LEXIS 5127] 

Rule: A traffic stop must be completed during the time it reasonably takes to complete the mission of the traffic stop.  The mission of a traffic stop may be extended when a reasonable suspicion of other criminal activity is discovered.  A vehicle may be lawfully seized whenever there exists probable cause to believe it contains contraband. A search warrant is not needed to conduct a probable cause search of a vehicle. 

Facts:  On August 12, 2022, Nevada State Trooper William Boyer observed a BMW driving at 89 mph (“well above the posted speed limit”) near Wells, Nevada.  In a contact recorded by the trooper’s bodycam and his vehicle’s dashcam, the Trooper Boyer made a traffic stop at 3:51 p.m.  Defendant Triston Harris Steinman was soon identified as the vehicle’s driver and only occupant.  As Trooper Boyer walked up to the passenger-side window, he observed “movement within the vehicle’s cab.” He could also see in plain sight an ammunition box on the front right floor.  On the back seat was a blanket covering unknown items.  Upon obtaining defendant’s license and registration, defendant told the trooper that he was moving from Washington to Utah and just passing through Nevada.  While talking about this, Trooper Boyer inquired about what was under the blanket in the back seat, to which defendant responded, “stuff;” declining to elaborate.  Defendant eventually admitted to having ammunition in the ammo box, but denied having any guns.  

Trooper Boyer returned to his patrol car to run a driver’s license check to verify the validity of defendant’s license and check whether he had any outstanding warrants or protection orders.  Finding none, the trooper returned to defendant and his vehicle and checked to make sure the vehicle’s VIN number matched the registration.  He also asked for defendant’s proof of insurance.  Suspecting that based upon the above, defendant might constitute a safety risk, Trooper Boyer asked defendant to come and sit in his patrol car, a request that defendant declined, asking instead if he could just get his ticket and leave. Defendant complied, however, after the trooper told defendant that he had the legal authority to order him out of the car.  

With defendant sitting in the front seat of the patrol car, Trooper Boyer accessed a “ticket-writer application” through his vehicle’s computer.  As he did so, he noticed that defendant appeared to be sweating despite the air-conditioner running in the cruiser.  As he worked on the citation on the computer, Trooper Boyer conversed with defendant about his travel plans and his history while working.  

At approximately ten minutes into the stop (4:01 p.m.), Trooper Boyer requested a criminal history check on defendant as defendant again asked if he could just get his ticket and leave. Being told that the ticket-writing process was not yet complete, they continued conversing while Trooper Boyer worked on the citation. At about 4:05 p.m., about three to four minutes after requesting a criminal history check, Trooper Boyer received the printed results.  It took Trooper Boyer another three-and-a half to four minutes to review the criminal history information, noting that there was at least one “felony with a guilty disposition” listed.  At this point, it was 4:08 p.m.; 17 minutes into the traffic stop.  At this point in time, Trooper Boyer effectively paused the citation-writing process as he continued to converse with defendant about the parameters of the ticket that he was about to issue.  He finally had defendant sign the ticket at about 4:10 p.m.  Deputy Boyer then finished filling out other fields in the ticket-writer application while chatting with defendant about other stuff like how he obtained the money to purchase his BMW.  

The trooper then asked defendant whether he had ever been in any trouble, to which defendant responded; “A little bit.”  Defendant admitted to the trooper that he had an assault charge but that he did not think he had any felonies (in apparent contradiction to the records check information the trooper had received) other than when he was a juvenile. Trooper Boyer asked defendant if he still shot guns, to which defendant responded, “Not really.” Defendant then commented that the ammunition in his car was there because he was bringing it home. Trooper Boyer continued filling out the citation as he explained the applicable fine he would have to pay.  At approximately 4:20 pm—just under thirty minutes into the stop—Trooper Boyer informed defendant that according to the criminal history check that was made, he did in fact have some felonies on his record.  He also told defendant that the ammunition in his BMW provided him with probable cause to search the car.  Defendant declined, however, when asked for permission to search the car.  Defendant claimed at that point that the ammunition box was in fact empty despite his earlier admission that it was not.  Upon the arrival of other officers, Trooper Boyer unsuccessfully attempted to secure a K-9 unit.  However, defendant’s felony convictions (and not just felony “charges”) were confirmed, and a tow truck was requested.  

At 4:38pm, Trooper Boyer finished explaining the citation to defendant and returned some of his documentation. The trooper then explained to defendant that the BMW was being seized and that he would not have access to it.  At approximately 5:25 p.m.—about ninety minutes after defendant was first stopped—defendant received his license back. The tow company arrived shortly thereafter and took the BMW.  A search warrant was subsequently obtained for the car.  The resulting search resulted in the recovery of a literal arsenal of firearms (38 of them), silencers, ammunition, marijuana, and drug paraphernalia. A loaded firearm was also found directly beneath the driver’s seat, within defendant’s easy reach.  Charged in federal court with a host of firearms- and ammunition-related offenses, defendant’s motion to suppress was granted by the district (trial) court.  The Government appealed.

Held: The Ninth Circuit Court of Appeals reversed, remanding the case back to the district court for trial.  On appeal, three primary issues were discussed:  

(1) Prolongation of the Traffic Stop: The trial court magistrate ruled that the fruits of the traffic stop were to be suppressed because Trooper Boyer unconstitutionally extended the traffic stop beyond the time that was needed to complete the “mission of the traffic stop” without the requisite reasonable suspicion of some other criminal activity necessary to delay defendant’s release.  

The Ninth Circuit disagreed. The rules are well established: “A seizure for a traffic violation justifies a police investigation of that violation.” (See Rodriguez v. United States (2015) 575 U.S. 348, 354.) However, “(t)o be lawful, a traffic stop must be limited in its scope: an officer may ‘address the traffic violation that warranted the stop,’ make ‘ordinary inquiries incident to the traffic stop,’ and ‘attend to related safety concerns.’” . . . “The stop may last ‘no longer than is necessary to effectuate’ these purposes and complete the traffic ‘mission’ safely.” . . . “Authority for the seizure . . . ends when tasks tied to the traffic infraction are—or reasonably should have been—completed.” (Italics added.) . . .  “Lawful inquiries incident to a traffic stop can include checking a driver’s license, determining whether there are outstanding warrants, and inspecting the automobile’s registration and proof of insurance. . . .”  It is also lawful to “attend to the officer’s safety concerns.” “Attending to related safety concerns includes ‘certain negligibly burdensome precautions in order to complete [the traffic] mission safely.’ . . . ‘So, for example, an officer may order the driver of a vehicle to exit the vehicle during a traffic stop.’ . . .  These safety precautions fall within the mission of the traffic stop because “[t]raffic stops are ‘especially fraught with danger to police officers.’” Should an officer extend the traffic stop beyond that time it would reasonably take to complete the “mission of the traffic stop,” however, he is then violating the Fourth Amendment.  

An exception to this rule is when the officer develops additional reasonable suspicion of some criminal activity beyond the traffic violation itself.  “(A) stop ‘may be extended to conduct an investigation into matters other than the original traffic violation’ so long as ‘the officers have reasonable suspicion of an independent offense.’”  (United States v. Taylor (9th Cir. 2023) 60 F.4th 1233, 1239.)  The issue in this new case, therefore, was whether the stop was prolonged beyond the time it should have taken to complete the mission of the traffic stop, and, if so, was the prolongation of the detention justified by a reasonable suspicion of some other criminal activity based on the information available at the time.   Disagreeing with the district court, the Ninth Circuit held that although the stop was in fact prolonged, such prolongation was justified by additional reasonable suspicion of criminal activity.  

In analyzing this issue, the Court first looked at the traffic stop itself.  It then considered when, if ever, reasonable suspicion of some criminal activity other than the speeding violation was developed.  In this case, that additional reasonable suspicion was found to have been developed at approximately 4:08 p.m., 17 minutes after the initial stop, when Trooper Boyer learned that defendant had a felony criminal record.  Up until that point in time, the Ninth Circuit ruled that Trooper Boyer was engaged in the mission of the traffic stop only. Asking defendant a number of questions when initially stopped while checking his documentation, ordering him out of his BMW and into the patrol car (done for safety reasons), and asking him questions while filling out a traffic citation, were all legitimate parts of the mission of the traffic stop.  Requesting, waiting for, and then reviewing defendant’s criminal history, were either (1) allowed as a part of the mission of the traffic stop, or (2) did not unlawfully prolong the stop. But then, upon learning that defendant had a felony record, the trooper from that point on had a reasonable suspicion to believe that defendant was engaged in criminal activity beyond the speeding for which he had originally been stopped; i.e., that he (as a convicted felon) illegally possessed ammunition (if not a firearm); a fact which defendant had already admitted.  Thus, assuming that Trooper Boyer did in fact prolong the stop upon learning that defendant had a felony record, while already knowing that defendant possessed ammunition, he had a legal right to do so in order to allow time to further investigate that violation of the law. Also, assuming that defendant was correct in alleging that some of Trooper Boyer’s questioning prior to discovering his felony record fell outside the purview of the traffic-stop mission, doing so did not violate his Fourth Amendment rights. That’s because “the Fourth Amendment tolerate[s] certain unrelated investigations that [do] not lengthen the roadside detention.” (Rodriguez, at pg. 354.) 

The key inquiry is whether the questioning Trooper Boyer engaged in before discovering defendant criminal history “measurably extend[ed] the duration of the stop.” (Arizona v. Johnson (2009) 555 U.S. 323, 333.)  The Court ruled here that such questions were asked as Trooper Boyer continued to fill out the citation, and did not delay the process.  In so ruling, the Court rejected defendant’s argument that Trooper Boyer’s simultaneous questioning while filling out the ticket inherently slowed down the citation-writing process, and thus extended the traffic stop (being “distracting” and “reduc(ing) the capacity of officers to work diligently”).  As noted by the Court: “Police officers are not automatons required to work with the maximum possible efficiency at all costs. Nor are they required to sit in stony silence like schoolchildren taking an exam during the process of filling out a traffic citation.”  Ultimately, “(T)he key inquiry is whether the questioning measurably extend[ed] the duration of the stop.” (Johnson, 555 U.S. at 333.)  Here, the Court held that it did not.  Nothing in the record (all of which was memorialized by Trooper Boyer’s body camera) supports defendant’s argument that the trooper “measurably extend(ed) the duration of the traffic stop” up until developing a reasonable suspicion that defendant illegally possessed ammunition.  Then, once the trooper developed that reasonable suspicion, he could lawfully prolong the detention for the purpose of investigating defendant’s possible illegal use of firearms.  

Defendant also contested the Court’s conclusion that learning of defendant’s prior felony record after defendant had admitted to having ammunition in the ammunition box established the necessary reasonable suspicion to prolong the detention.  Noting that a “(r)easonable suspicion ‘exists when an officer is aware of specific, articulable facts which, when considered with objective and reasonable inferences, form a basis for particularized suspicion,’” the Court held that Trooper Boyer did in fact have “at least” a reasonable suspicion upon learning of defendant’s prior felony record, and that from that point on, the trooper was allowed to lawfully extend the detention in order to investigate his possible possession of a firearm.  

(2) Probable Cause to Seize (Impound) the BMW: When defendant declined Trooper Boyer’s request for permission to search his BMW, the car was impounded pending the obtaining of a search warrant.  The district court ruled that the trooper did not have probable cause justifying the seizure.  The Ninth Circuit disagreed.  It is clear that the towing of defendant’s BMW constituted a “seizure,” under the Fourth Amendment.  As such, it was the Government’s burden to prove that the warrantless impoundment of defendant’s car came within an exception to warrant requirement.  Defendant did not argue, however, that the trooper did not have probable cause to believe that his car contained ammunition.  Defendant’s argument, instead, was that a felon possessing ammunition is not a violation of Nevada’s state law (see Nev. Rev. Stat. Ann. § 202.360; prohibiting ownership or possession of a “firearm” only, not making any reference to ammunition).  And even though it is a violation of federal law for a felony to possess ammunition (see 18 U.S.C. § 922(g)(1)), Trooper Boyer, as a Nevada state trooper, had no authority to enforce the federal law.  Surprisingly enough, there is no persuasive case law on this issue.  So the Ninth Circuit elected to provide the missing authority by ruling for the first time that a state law enforcement officer does in fact have the legal authority to enforce federal law.  

The Court reached this conclusion by first noting that the Supremacy Clause makes it clear that federal law is “the supreme Law of the Land.”  (U.S. Const., art. VI, cl. 2.)  Secondly, the Fourth Amendment has been incorporated against the states, rendering it the federal standard whose protections do not vary from jurisdiction to jurisdiction. (See Virginia v. Moore (2008) 553 U.S. 164, 172.)  Third, the Ninth Circuit has previously held that “[t]he general rule is that local police are not (specifically) precluded from enforcing federal statutes.” (Gonzales v. City of Peoria (9th Cir. 1983) 722 F.2nd 468, 474.), noting that there is no Nevada law prohibiting its officers from enforcing federal law.  Fourth, other federal circuits have held in closely related circumstances that evidence of federal crimes may be seized by state officers if that evidence is in plain view. (See United States v. Smith (1st Cir. 1990) 899 F.2nd 116, 118; United States v. Smith (1st Cir. 1990) 899 F.2nd 116, 118; and United States v. Le (10th Cir. 1999) 173 F.3rd 1258, 1271.) And fifth, the Court noted that the rule requiring suppression of evidence is an extraordinary remedy that carries a substantial cost to society.  (Citing Davis v. United States (2011) 564 U.S. 229, 237) Per the Supreme Court; “although ‘the ‘bitter pill’ of suppression must be swallowed when necessary to deter Fourth Amendment violations, it remains a ‘last resort.’”  (Id., quoting Hudson v. Michigan (2006) 547 U.S. 586, 591.) Based upon all this, the Ninth Circuit declined to “administer the harsh medicine of suppression here simply because the BMW was seized because it contained evidence of a violation of federal law rather than state law.”  Further, even if the Court were to agree that Trooper Boyer was without the authority to enforce federal law, the Court also held that probable cause existed under the circumstances to believe that defendant (as a felon) illegally possessed a firearm as well as ammunition.  Specifically, the Court first intimated that defendant’s admission to possessing ammunition was sufficient in itself to constitute probable cause to believe that he also possessed firearms in his vehicle.  However, even if not enough, the trooper certainly had probable cause when in addition to being told about the ammunition, the trooper also considered the defendant’s furtive movements as he approached the defendant’s car, shortly thereafter seeing a blanket in the back seat that appeared to cover a number of items, plus defendant’s evasive response when asked what was under the blanket with simply that it was “stuff.”  These circumstances in combination, per the Court, were sufficient to provide the necessary probable cause to believe defendant possessed a firearm and impound defendant’s BMW.                    

(3) The Alleged Overbreadth of the Search Warrant: The district court ruled that the warrant was overbroad and that for this reason alone, the subsequent search of the BMW was illegal.  The Government did not contest this ruling, but rather argued on appeal that because Trooper Boyer had probable cause to search the vehicle, he didn’t need a warrant in the first place.  The Ninth Circuit agreed.  In Coolidge v. New Hampshire (1971) 403 U.S. 443, 453, the Supreme Court clarified that evidence seized pursuant to a defective warrant may still be admitted if the search resulting in the seizure of evidence was lawful under “some other theory,” including exceptions to the warrant requirement.  As a result, “courts across the nation have declined to suppress the fruits of searches that were conducted pursuant to a defective warrant if an exception to the warrant requirement would otherwise have justified the search.” (E.g., see United States v. Martinez (8th Cir 1996) 78 F.3rd 399, 401; United States v. McCoy (1st Cir. 1992) 977 F.2nd 706, 710; United States v. Poole (4th Cir. 1983) 718 F.2nd 671, 675; United States v. Clark (5th Cir. 1977) 559 F.2nd 420, 426; and also Commonwealth v. Campbell (VA. 2017) 807 S.E.2nd 735, 738-739.)  Further, the Court rejected the defendant’s argument that because Trooper Boyer chose to proceed by way of a search warrant, he was stuck with that choice.  To the contrary, the resulting evidence is admissible so long as there exists some constitutional means of retrieving it.  In this case (although not discussed in the Court’s decision), piles of cases have held that a law enforcement officer may conduct a warrantless search of a vehicle so long as probable cause exists to believe it contains seizable evidence which, as noted above, was the excat circumstance in this case.  (E.g., see Carroll v. United States (1925) 267 U.S. 132, 150-153.)  

(4) Conclusion: The district court was overruled on all of its rulings relevant to this appeal.  The district court’s dismissal of the case was reversed with the matter remanded for trial.

Note: Excellent job by Nevada State Trooper William Boyer who took his time, reacted appropriately to a suspect who was obviously hiding something, and took steps to ensure his own safety, all the while conducting his investigation by the book.  The only viable issue I saw—but which the Court kind of po-pooed—was the length of time it took to develop the necessary reasonable suspicion to justify prolonging defendant’s detention; i.e., some 17 minutes.  Courts tend to consider 10 to 12 minutes as all that is needed to complete the so-called “mission of the traffic stop.”  (E.g., see United States v. Gorman (9th Cir. 2017) 859 F.3rd 706, 714-719, where “less than 10 minutes is acceptable.”; United States v. Goodwill (7th Cir. 2022) 24 F.4th 612; a traffic stop followed by the use of a K-9 to search for and alert on cocaine in the car, all accomplished within 10 minutes; and People v. Gyorgy (2023) 93 Cal.App.5th 659; 11 minutes and 54 seconds.)  While maybe pushing the envelope on this issue, Trooper Boyer at least used those 17 minutes wisely, limiting himself to matters that are traditionally considered a part of the mission of a traffic stop. What is disturbing in this case is the fact that Trooper Boyer was obviously familiar with what he could and could not do during a traffic stop, working hard to comply with all the rules he’d been taught, and then erring on the side of caution by securing a search warrant when a warrant wasn’t needed, only to be told by a federal magistrate—who one would think should know the rules even better—that he’d screwed it all up.  I’m sure, however, the trooper will learn shortly (if he hasn’t already) that he apparently knows the law better than the magistrate.  Good job.