In which scenario is it appropriate to detain an individual without a warrant?

Detaining an individual without a warrant is appropriate when there is probable cause or reasonable suspicion to believe that the individual is involved in criminal activity. Probable cause refers to a reasonable belief, based on facts and circumstances known to the officer, that a crime has been committed or will be committed. Reasonable suspicion is a lower standard than probable cause and allows officers to briefly detain a person for the purpose of investigation if they have specific and articulable facts that suggest criminal activity may be afoot.

In practice, this means that if an officer observes behavior that leads them to reasonably suspect that a person is engaged in illegal activity, they may stop and briefly detain the individual to gather more information, such as asking questions or conducting a pat-down for weapons if they believe the person might be armed and dangerous. This is in accordance with established legal standards aimed at balancing individual rights with the need for effective law enforcement.

While the other scenarios suggest conditions under which an individual might be detained, they do not capture the legal framework necessary for warrantless detentions as effectively as the concept of probable cause or reasonable suspicion does. For example, just appearing suspicious does not meet the legal threshold for detention unless supported by specific facts, and being under investigation does not automatically justify