Border Patrol agents at an immigration checkpoint discovered a large stash of marijuana in a car driven by defendant Miguel Machuca-Barrera. Machuca-Barrera was convicted of possession with intent to distribute marijuana. We hold that because the brief stop by the Border Patrol lasted no longer than necessary to fulfill its immigration-related purpose, the stop did not violate the Fourth Amendment. Further, because the prosecutor's closing argument did not go beyond reasonable inferences that could have been drawn from the record, the prosecutor's statements did not deprive Machuca-Barrera of a fair trial. We affirm.

* On March 21, 1999, two teenage boys driving a Plymouth Laser entered a permanent immigration checkpoint near Marfa, Texas.1 It was about 6:45 p.m. on a Sunday afternoon. Border Patrol Agent Sean Patrick Holt questioned the pair about their travel plans and citizenship. Miguel Machuca-Barrera, 19, and Aldo Venegas-Muniz, 15, replied that they were U.S. citizens living in Pecos, Texas, and that they were returning from a weekend trip to Ojinaga, Mexico.

At this point, Agent Holt asked them whether they were carrying any firearms or drugs.2 Machuca-Barrera replied no. Agent Holt requested consent to search the car, which Machuca-Barrera gave. Agent Holt then referred them to the secondary inspection area. In the secondary inspection area, Agent Holt ordered the boys to exit the car. Border Patrol Agent Guadalupe Trevino Jr. then led his drug-sniffing dog around the car. The dog alerted near the trunk of the car.

With some difficulty, the agents were finally able to locate drugs in the car. The agents removed a large speaker box in the rear of the car. The box contained two holes, which had been covered by pieces of wood. Inside the box were over 43 pounds of marijuana.

Machuca-Barrera was indicted for possession with intent to distribute marijuana.3 Before trial, he moved to suppress the drugs found, making essentially the same arguments now presented to this court. The district court denied the motion.

At trial, Machuca-Barrera testified that he knew nothing of the drugs in the car. He testified that he had gone with Venegas-Muniz to Ojinaga to party, because they could get alcohol more easily in Mexico. While in Ojinaga, however, the car was out of his control several times: when he got a flat tire repaired, when he got the speakers repaired, and when Venegas-Muniz borrowed it.4

He also explained the condition of the speaker box. This testimony was corroborated by his cousin Andres Machuca, who testified that he and Machuca-Barrera had installed the speaker box in the car, but their speaker system was designed to be sealed. Since the only correct-size box available had holes in it, they covered the holes to make the speakers sound better.

In his closing argument, the prosecutor attacked the credibility of Andres Machuca:

Andres admitted . . . that he hadn't told anybody his story about the speaker box before today. Now, don't you think that if your cousin . . . was in a bind that this Defendant is in you would have brought that up before the day of trial? You wouldn't have made it up after you heard what was testified to in the courtroom about the wooden blocks and come in here and sold it as truth--

At this point defense counsel objected, stating, "There's no evidence that he made it up after he heard." The district court overruled the objection.

Machuca-Barrera was found guilty by the jury, and sentenced to 30 months for the drug possession charge. He appeals.

Machuca-Barrera's primary argument is that Agent Holt's inquiry about drugs violated the Fourth Amendment because it was not based on reasonable suspicion.

* In United States v. Martinez-Fuerte5 the Supreme Court upheld the constitutionality of immigration checkpoints at which INS agents would stop travelers without suspicion for questioning about immigration status. The Court held that suspicionless "stops for brief questioning routinely conducted at permanent checkpoints are consistent with the Fourth Amendment."6 It explicitly limited its holding to stops and questioning to enforce the immigration laws; searches or "further detention . . . must be based on consent or probable cause."7 Thus, the Supreme Court created a narrow exception to the general requirements of reasonable suspicion and probable cause.8

The Supreme Court was recently faced with suspicionless stops at checkpoints created to interdict drugs. City of Indianapolis v. Edmond9 held such checkpoints unconstitutional.10 The Court stated that the validity of suspicionless stops at a checkpoint depends on the "programmatic purpose" of the checkpoint.11 It pronounced, "We have never approved a checkpoint program whose primary purpose was to detect evidence of ordinary criminal wrongdoing."12 The government's interest in intercepting illegal drugs, the Court held, was indistinguishable from the government's interest in "ordinary crime control."13 The special "problems of policing the border" for illegal immigrants distinguished the checkpoints approved in Martinez-Fuerte.14

In short, checkpoints with the primary purpose of identifying illegal immigrants are constitutional, and checkpoints with the primary purpose of interdicting illegal drugs are not. As we now explain, this distinction is crucial to determining the lawful scope and duration of detentions at immigration checkpoints.15 The Supreme Court has not explained the constitutional boundaries of individual stops at immigration checkpoints, however. We thus turn to the law on the constitutional scope and duration of stops based on reasonable suspicion for guidance.

In reviewing stops based on reasonable suspicion, the Supreme Court and this court have long held that the justifying purpose of a stop constrains its lawful extent. As we have stated, "[t]he Constitution [is] violated [ ] when the detention extend[s] beyond the valid reason for the initial stop."16 For example, in the typical case of an automobile stop, a seizure is unjustified in the absence of reasonable suspicion of unlawful activity. Thus, when an officer stops a person based on reasonable suspicion of some crime, the officer may detain that person for only long enough to investigate that crime. Once the purpose justifying the stop has been served, the detained person must be free to leave.17

To determine the lawfulness of a stop, we ask whether the seizure exceeded its permissible duration. We look to the scope of the stop in order to determine its permissible duration.18 The permissible duration of the stop is limited to the time reasonably necessary to complete a brief investigation of the matter within the scope of the stop.19 The scope of a stop is limited to investigation of matters justifying the stop.

An officer may ask questions outside the scope of the stop, but only so long as such questions do not extend the duration of the stop. It is the length of the detention, not the questions asked, that makes a specific stop unreasonable:20 the Fourth Amendment prohibits only unreasonable seizures, not unreasonable questions, and law enforcement officers are always free to question individuals if in doing so the questions do not effect a seizure.21

The Fourth Amendment's requirement that stops be reasonable applies equally to a checkpoint. Because stops at an immigration checkpoint need not be justified by reasonable suspicion, however, we do not ask the stopping officer to articulate a justification for the stop. Instead, the justification for an immigration checkpoint stop comes from its programmatic purpose. Edmond stands for the principle that it is a legitimate, programmatic purpose that justifies a checkpoint stop made without any suspicion.

We have already noted that the permissible duration of the stop is limited to the time reasonably necessary to complete a brief investigation of the matter within the scope of the stop. The scope of an immigration checkpoint stop is limited to the justifying, programmatic purpose of the stop: determining the citizenship status of persons passing through the checkpoint.22 The permissible duration of an immigration checkpoint stop is therefore the time reasonably necessary to determine the citizenship status of the persons stopped.23 This would include the time necessary to ascertain the number and identity of the occupants of the vehicle, inquire about citizenship status, request identification or other proof of citizenship, and request consent to extend the detention.

The permissible duration of an immigration checkpoint stop is therefore brief. Indeed, the brevity of a valid immigration stop was a principal rationale for the Supreme Court's conclusion in Martinez-Fuerte that immigration checkpoints are constitutional: "The stop does intrude to a limited extent on motorists' right to free passage without interruption . . . [b]ut it involves only a brief detention of travelers during which [a]ll that is required of the vehicle's occupants is a response to a brief question or two and possibly the production of a document evidencing a right to be in the United States."24

Within this brief window of time in which a Border Patrol agent may conduct a checkpoint stop, however, we will not scrutinize the particular questions a Border Patrol agent chooses to ask as long as in sum they generally relate to determining citizenship status.25 Law enforcement officers must have leeway in formulating questions to determine citizenship status. We decline a protocol that measures the pertinence of questions to the immigration purpose by an after-the-fact standard for admissibility at trial. So long as a checkpoint is validly created, policing the duration of the stop is the most practical enforcing discipline of purpose. The key is the rule that a stop may not exceed its permissible duration unless the officer has reasonable suspicion. We deploy a test that is both workable and which reinforces our resistance to parsing the relevance of particular questions. To scrutinize too closely a set of questions asked by a Border Patrol agent would engage judges in an enterprise for which they are ill-equipped and would court inquiry into the subjective purpose of the officer asking the questions.26

Of course, a Border Patrol agent may extend a stop based upon sufficient individualized suspicion. For extended detentions or for searches, Martinez-Fuerte requires consent or probable cause.27 Also, if the initial, routine questioning generates reasonable suspicion of other criminal activity, the stop may be lengthened to accommodate its new justification.28 Thus, an agent at an immigration stop may investigate non-immigration matters beyond the permissible length of the immigration stop if and only if the initial, lawful stop creates reasonable suspicion warranting further investigation.29

In this case, it is not disputed that the primary purpose of the Marfa checkpoint is to investigate immigration status.30 Thus, we face only the question of whether the suspicionless stop of Machuca-Barrera was sufficiently limited in duration to pass constitutional muster.31 We note initially that our inquiry considers only Agent Holt's questioning of Machuca-Barrera up to the point at which Machuca-Barrera consented to a search of his car.32 After Machuca-Barrera consented to a search, Agent Holt needed no justification to prolong the encounter.33

The justified scope of the stop was immigration-related questions. Therefore, the permissible duration of the stop was the amount of time reasonably necessary for Agent Holt to ask a few questions about immigration status. Agent Holt's few questions took no more than a couple of minutes; this is within the permissible duration of an immigration checkpoint stop. Although Machuca-Barrera notes that Agent Holt asked a question about drugs, we will not second-guess Agent Holt's judgment in asking that question. The brief stop by Agent Holt, which determined the citizenship status of the travelers and lasted no more than a couple of minutes before Agent Holt requested and received consent to search, was constitutional.

Machuca-Barrera challenges the prosecutor's arguments insinuating that Andres Machuca made up his corroborating testimony after hearing trial testimony, saying that they had no basis in the evidence. In fact, Machuca-Barrera argues, the record reflects that Andres was not in the courtroom when other witnesses testified.34 As a consequence, he concludes, the prosecutor unfairly influenced the jury and deprived him of a right to a fair trial.

In reviewing a claim of prosecutorial misconduct in arguing to the jury, we decide whether the remarks were improper and, if so, evaluate whether the remarks affected the substantial rights of the defendant.35 If they did not, the error is harmless and does not justify reversal.36

A prosecutor may argue "those inferences and conclusions he wishes [the jury] to draw from the evidence so long as those inferences are grounded upon the evidence."37 But "a prosecutor's closing argument cannot roam beyond the evidence presented during trial."38 In assessing the prosecutor's statements in this case, "it is necessary to look at them in context."39

It is true that the specific fact of Andres Machuca being in the courtroom is not in the record. In context, however, the prosecutor's suggestions that the witness's testimony was recently fabricated were grounded in the record and represented an argument about reasonable inferences that the prosecutor invited the jury to draw. Given that the witness had not told his story prior to trial, a reasonable juror could infer that if his story were true, he would have offered it sooner to help Machuca-Barrera. The assertion that Andres Machuca could not have heard Machuca-Barrera's testimony in the courtroom does not contradict the substance of the prosecutor's argument; the jury need only infer that Andres Machuca had heard at some point "what was testified to in the courtroom about the wooden blocks." Consequently, the district court did not err in overruling Machuca-Barrera's objection to the prosecutor's comment.

The judgment of the district court is AFFIRMED.