This is a fascinating case on reasonable suspicion calculus and what an appellate court is expected to do in judicial review, rather than rubber stamping the trial court’s conclusion reasonable suspicion existed. Two guys standing around, one with a prior, doesn’t support a stop of both, let alone the other. Seeing a gun is not reasonable suspicion in an open carry state. United States v. Black, 707 F.3d 531 (4th Cir. 2013):

In Terry v. Ohio, Chief Justice Earl Warren recognized that police officers need discretion to perform their investigative duties. 392 U.S. 1 (1968). Since Terry, this discretion has been judicially broadened, giving police wide latitude to fulfill their functions. In some circumstances, however, police abuse this discretion, and we must remind law enforcement that the Fourth Amendment protects against unreasonable searches and seizures. Because in this case, we find the police disregarded the basic tenets of the Fourth Amendment, we reverse.

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These factors persuade us that long before he was told not to leave, Black was seized for purposes of the Fourth Amendment. Specifically, we hold that in view of all these circumstances, Black was seized at the point when Officer Zastrow pinned Black’s ID to his uniform, while Officer Strayer frisked the men in the group. The verbal directive from the officers not to leave was not the initiation of the seizure, but rather an affirmation that Black was not free to leave. Black’s subsequent decision to leave does not negate the finding that reasonable person in Black’s circumstances would not feel free to leave. Instead, Black’s decision to leave was an effort to terminate an illegal seizure.

. . . There is no reasonable suspicion merely by association.

. . .

At least four times in 2011, we admonished against the Government’s misuse of innocent facts as indicia of suspicious activity. See United States v. Powell, 666 F.3d 180 (4th Cir. 2011); Massenburg, 654 F.3d 480; United States v. Digiovanni, 650 F.3d 498 (4th Cir. 2011); and United States v. Foster, 634 F.3d 243 (4th Cir. 2011). Although factors "susceptible of innocent explanation," when taken together, may "form a particularized and objective basis" for reasonable suspicion for a Terry stop, United States v. Arvizu, 534 U.S. 266, 277-78 (2002), this is not such a case. Instead, we encounter yet another situation where the Government attempts to meet its Terry burden by patching together a set of innocent, suspicion-free facts, which cannot rationally be relied on to establish reasonable suspicion.

First, Officer Zastrow’s suspicion that a lone driver at a gas pump who he did not observe drive into the gas station is engaged in drug trafficking borders on absurd. ... [¶] Second, Gates’ prior arrest history cannot be a logical basis for a reasonable, particularized suspicion as to Black. Without more, Gates’ prior arrest history in itself is insufficient to support reasonable suspicion as to Gates, much less Black. ...

Third, it is undisputed that under the laws of North Carolina, which permit its residents to openly carry firearms, see generally N.C. Gen. Stat. §§ 14-415.10 to 14-415.23, Troupe’s gun was legally possessed and displayed. The Government contends that because other laws prevent convicted felons from possessing guns, the officers could not know whether Troupe was lawfully in possession of the gun until they performed a records check. Additionally, the Government
avers it would be "foolhardy" for the officers to "go about their business while allowing a stranger in their midst to possess a firearm." We are not persuaded.

Being a felon in possession of a firearm is not the default status. More importantly, where a state permits individuals to openly carry firearms, the exercise of this right, without more, cannot justify an investigatory detention. ...

Fourth, with respect to the officers’ "Rule of Two" or "one plus rule," we would abdicate our judicial role if we took law enforcement-created rules as sufficient to establish reasonable suspicion. "The essential purpose of the proscriptions in the Fourth Amendment is to impose a standard of ‘reasonableness’ upon the exercise of discretion by government officials, including law enforcement agents, in order to safeguard the privacy and security of individuals against arbitrary invasions." Delaware v. Prouse, 440 U.S. 648, 653-54 (1979) (citation and quotation marks omitted). As such, we must consider whether, in applying law enforcement rules, there are safeguards "to assure that the individual’s reasonable expectation of privacy is not subject to the discretion of the official in the field." Id. at 655 (citation and quotation marks omitted).

Also, acquiescence to police authority is a stop:

3. The Government argues that in determining whether a seizure occurred, we should apply the "force or submission" standard set forth in Hodari D., where the Supreme Court stated, "[a]n arrest requires either physical force ... or, where that is absent, submission to the assertion of authority." 499 U.S. at 626 (emphasis omitted). The Government intends that in applying Hodari D., we would reach the conclusion that Black was seized only when Officer Zastrow exerted physical force by grabbing Black’s bicep. In Brendlin v. California, the Supreme Court clarified Hodari D., stating that "[w]hen the actions of the police do not show an unambiguous intent to restrain or when an individual’s submission to a show of governmental authority takes the form of passive acquiescence," Hodari D.’s force or submission test yields to Mendenhall’s free to leave, totality of the circumstances test. 551 U.S. 249, 255 (2007). Here, we find that at the time the officers arrived and seized Troupe’s gun, their actions did not convey an unambiguous intent to restrain Black, and Black’s submission to the officers’ authority was in essence passive acquiescence, and thus, Mendenhall, as opposed to Hodari D. applies.