In his brief concurrence, Justice Hugo Black noted that he concurs with the judgment and opinion of the Court in this case except where it quotes from Katz v. United States (1967) and the concurring opinion in Warden v. Hayden (1967).

In his concurring opinion, Justice John Marshal Harlan II joined in the Court’s judgment but stated that he wrote separately to “fill in a few gaps, as I see them, in its opinion.” Harlan emphasized that an officer’s authority to conduct an on-the-street stop and frisk was bounded by the Fourth Amendment and depended on whether the activity was “reasonable under the circumstances as the officer credibly relates them in court.” Because Ohio didn’t provide statutory authority for police to frisk a suspect based on suspicion generally, Harlan argued that the state court correctly rested its decision on the narrower principle that “when an officer is lawfully confronting a possibly hostile person in the line of duty he has a right, springing only from the necessity of the situation and not from any broader right to disarm, to frisk for his own protection.” Harlan viewed this as “the only satisfactory basis I can think of for affirming this conviction,” but noted that it contained “two logical corollaries that I do not think the Court has fully expressed.”

Regarding the first corollary, Harlan argued that before a protective search could occur, “if the frisk is justified in order to protect the officer during an encounter with a citizen, the officer must first have constitutional grounds to insist on an encounter, to make a forcible stop.” He reasoned that while any citizen or officer possessed the liberty to address questions to others, an individual normally retained an equal right to ignore inquiries and walk away. Thus, he stated, “I would make it perfectly clear that the right to frisk in this case depends upon the reasonableness of a forcible stop to investigate a suspected crime.” Under the second corollary, Harlan asserted that “[w]here such a stop is reasonable, however, the right to frisk must be immediate and automatic if the reason for the stop is, as here, an articulable suspicion of a crime of violence.” He stressed that “[t]here is no reason why an officer, rightfully but forcibly confronting a person suspected of a serious crime, should have to ask one question and take the risk that the answer might be a bullet.”

Applying these principles, Harlan argued that McFadden lacked probable cause for an arrest but possessed an articulable suspicion that Terry was planning a burglary or robbery. Because McFadden’s “justifiable suspicion afforded a proper constitutional basis for accosting Terry, restraining his liberty of movement briefly, and addressing questions to him,” the initial threshold of a lawful forced encounter was satisfied. As a result, Harlan concluded that “Officer McFadden’s right to interrupt Terry’s freedom of movement and invade his privacy arose only because circumstances warranted forcing an encounter with Terry in an effort to prevent or investigate a crime.” Once that threshold encounter was constitutionally justified, Harlan stated that “the officer's right to take suitable measures for his own safety followed automatically,” meaning that the seized revolvers were admissible as evidence.

In his concurring opinion, Justice Byron White joined the opinion of the Court but reserved judgment on “some of the Court’s general remarks about the scope and purpose of the exclusionary rule which the Court has fashioned in the process of enforcing the Fourth Amendment.” White noted that he wrote separately to address the constitutional status of street interrogation during an investigative stop, an issue he noted the majority had put aside. He observed that as a general matter, “[t]here is nothing in the Constitution which prevents a policeman from addressing questions to anyone on the streets,” and that “[a]bsent special circumstances, the person approached may not be detained or frisked but may refuse to cooperate and go on his way.” However, when suspicious circumstances justified police intervention, White maintained that “the person may be briefly detained against his will while pertinent questions are directed to him.”

Turning to the constitutional protections retained by the individual during such an interrogation, White stated that “the person stopped is not obliged to answer, answers may not be compelled, and refusal to answer furnishes no basis for an arrest, although it may alert the officer to the need for continued observation.” Regarding the legal foundation of the protective frisk, White asserted that “it is temporary detention, warranted by the circumstances, which chiefly justifies the protective frisk for weapons.” He reasoned that a frisk could serve preventive ends by signaling that suspicion had been aroused, regardless of whether questions were asked or answered. Ultimately, White concluded that “if the investigative stop is sustainable at all, constitutional rights are not necessarily violated if pertinent questions are asked and the person is restrained briefly in the process.”

In his dissenting opinion, Justice William Douglas agreed that petitioner was seized and frisked within the meaning of the Fourth Amendment but strongly dissented from the Court’s ruling that such intrusions could be constitutionally justified on less than probable cause. Douglas expressed a fundamental disagreement with the creation of a lower standard than probable cause, writing, “it is a mystery how that ‘search’ and that ‘seizure’ can be constitutional by Fourth Amendment standards, unless there was ‘probable cause’ to believe that (1) a crime had been committed or (2) a crime was in the process of being committed or (3) a crime was about to be committed.” Douglas pointed out that the Court itself disclaimed the existence of probable cause to believe Terry was committing a crime and observed that had an officer sought a warrant prior to the encounter, no magistrate could’ve issued one. Douglas criticized the majority for expanding executive discretion beyond judicial oversight, writing  that “[w]e hold today that the police have greater authority to make a ‘seizure’ and conduct a ‘search’ than a judge has to authorize such action. We have said precisely the opposite over and over again.”

Highlighting constitutional history, Douglas argued that warrantless searches and seizures had traditionally been constrained by the strict standard of probable cause and shouldn’t be replaced by vague concepts. He wrote, “[t]he term ‘probable cause’ rings a bell of certainty that is not sounded by phrases such as ‘reasonable suspicion.’” Tracing the Fourth Amendment’s origins back to the colonial rejection of general warrants and writs of assistance, Douglas observed that “common rumor or report, suspicion, or even ‘strong reason to suspect’ was not adequate to support a warrant for arrest” under established jurisprudence. He argued that departing from this historic standard compromised personal security, maintaining, “[t]he infringement on personal liberty of any ‘seizure’ of a person can only be ‘reasonable’ under the Fourth Amendment if we require the police to possess ‘probable cause’ before they seize him. Only that line draws a meaningful distinction between an officer’s mere inkling and the presence of facts within the officer’s personal knowledge which would convince a reasonable man that the person seized has committed, is committing, or is about to commit a particular crime.”

Douglas concluded by warning against bowing to societal pressures to dilute constitutional protections for the sake of police efficiency. He contended that granting law enforcement the power to conduct searches and seizures on suspicion represented a profound departure from constitutional design, writing that “[t]o give the police greater power than a magistrate is to take a long step down the totalitarian path.” Reaffirming the strict mandate of the Fourth Amendment, Douglas wrote, “[u]ntil the Fourth Amendment, which is closely allied with the Fifth, is rewritten, the person and the effects of the individual are beyond the reach of all government agencies until there are reasonable grounds to believe (probable cause) that a criminal venture has been launched or is about to be launched.” While Douglas acknowledged the “powerful hydraulic pressures throughout our history that bear heavily on the Court to water down constitutional guarantees and give the police the upper hand,” but he warned against eroding fundamental liberties. Ultimately, Douglas concluded that "if the individual is no longer to be sovereign, if the police can pick him up whenever they do not like the cut of his jib, if they can ‘seize’ and ‘search’ him in their discretion, we enter a new regime. The decision to enter it should be made only after a full debate by the people of this country.”