An officer may be able to stop a person and pat them down if the officer has reasonable suspicion that the person is armed and dangerous. This type of search, known as a "Terry stop" or a "stop and frisk," is based on the principle set forth in the United States Supreme Court case of Terry v. Ohio.

In order to conduct a Terry stop, an officer must have a reasonable, articulable suspicion that the person being stopped is armed and dangerous. The officer must be able to point to specific and objective facts that support this suspicion. Simply having a "hunch" or a general feeling that a person may be armed and dangerous is not sufficient to justify a Terry stop.

During a Terry stop, the officer is allowed to briefly detain the person and pat down the outside of their clothing to search for weapons. This search is limited to a "frisk" for weapons and is not intended to be a full search for evidence. If the officer finds a weapon during a Terry stop, they may seize it and may continue to detain the person for further investigation.

If the officer finds evidence of a crime during a Terry stop, they may seize the evidence and may use it as the basis for a more extensive search or for an arrest. However, if the officer does not find any weapons or evidence of a crime during a Terry stop, the person must be released.

This case answers the following question:Terry v. Ohio, 392 U.S. 1 (1968).

When, if ever, are a brief detainment and a limited, pat-down search permissible without a warrant?

The Fourth Amendment prevents a search or seizure of an individual without a warrant or an establish exception to this warrant requirement. Id. at 9. However, in certain situations, law enforcement officers may need to briefly stop an individual (a seizure) for questioning and may need to pay down the individual (a search) to ensure he or she doesn’t have any weapons. Id. at 10-11. The petitioner in this matter was subject to such a seizure and search, commonly called a “stop and frisk.” Id. at 7. The petitioner and two others were briefly stopped and asked their names by an officer. Id. The officer feared the three men were armed, so he performed a pat-down on each of them. Id. This revealed that two of the men were armed with handguns, which led to these two being convicted of carrying concealed weapons. Id. It was clear that no warrant was issued and that no exception to the warrant requirement existed to justify the officer’s actions. Id. at 9. Still, the Court determined that a new exception should exist to cover these limited searches for weapons based on reasonable suspicion. Id. at 21-22.

The Court acknowledged that petitioner had a reasonable expectation of privacy as far as his body was concerned, i.e., that he won’t be frisked by a government official. Id. However, the Court discussed the competing concerns the existed in these circumstances. Id. at 9-10. First, police must deal with “rapidly unfolding and often dangerous situations on city streets” and must react quickly based upon limited information. Id. at 10. However, the Fourth Amendment promises a long-recognized and championed right to be free from unreasonable searches and seizures. Id. at 11-12. Further, allowing too much discretion to officers will undoubtedly result in the quick swallowing of this right to privacy altogether. Id. at 12.

After weighing these competing interests, the Court decided to split the baby. Id. at 20. First, it disperses with any notion that a warrant must be required for a limited search, so long as the conduct is reasonable. Id. at 20-21. Reasonableness looks to two factors: the extent of the search and the justification the officer had to perform such actions. Id. at 21. Starting with the justification, the Court found that probable cause would be too demanding for the “necessarily swift action predicated upon the on-the-spot observations of the officer on the beat.” Id. at 20. Instead, the Court determined that an “officer must be able to point to specific and articulable facts which, taken together with rational inferences from those facts,” constitutes a reasonable suspicion that a stop-and-frisk are necessary. Id. at 21-22. Thus, “inarticulate hunches” are not enough to warrant action, but circumstances that would “warrant a man of reasonable caution” to act is enough. Id. at 22.

As for the amount of search activity that is permissible, the Court recognizes that the goal of such a frisk is officer safety, not gathering evidence of a crime. Id. at 24. On this basis, the Court held that this type of search for weapons must be “strictly circumscribed” to protect privacy interests guaranteed by the Fourth Amendment. Id. 25-26. This means the officer is very limited in what he or she may do: only that “which is necessary for the discovery of weapons which might be used to harm the officer.” Id. at 26. The Court found a pat down of outer clothing, with no intrusions into pockets was “confined…strictly to what was minimally necessary to learn whether the men were armed.” Id. at 30. If the officer feels a weapon, he may seize it; if he finds nothing, the activity is over and he can go no further. Id. at 29-30.