Which requirement is necessary for a pat down according to Terry v. Ohio?

The requirement for a pat down according to the ruling in Terry v. Ohio is reasonable suspicion that the individual may be armed. This landmark Supreme Court case established that law enforcement officers have the authority to stop and briefly detain a person if they possess reasonable suspicion that the individual is involved in criminal activity. Importantly, if during this stop the officer has a reasonable belief that the individual may be armed and poses a threat to their safety or the safety of others, they are permitted to conduct a limited search, known as a frisk, to ensure that the individual is not carrying a weapon.

This principle underscores the balance between individual rights and public safety, granting officers the ability to protect themselves during such encounters while adhering to constitutional standards. The justification for this search is solely based on the officer's perception of immediate danger and the need for safety, rather than any stronger standard such as probable cause or consent.