Final answer:
Police officers can apply the defense of public authority when their actions are within the scope of their official duties and when those actions are necessary to enforce laws or maintain public order. This authority is legitimate if used for official purposes like issuing a ticket for speeding or stopping a suspect based on reasonable suspicion. However, it cannot be used for personal services or actions that violate legal protections, such as the right against self-incrimination.
Step-by-step explanation:
Police officers are given a significant level of authority to enforce laws and maintain public order. This public authority is legitimate when used within the bounds of their officially designated duties. Whether issuing a speeding ticket for violating traffic laws or stopping and frisking a suspect based on reasonable suspicion, these actions are within the scope of police power. Nevertheless, this authority is limited and cannot be used to compel citizens to engage in personal services for an officer or to act unlawfully. For example, an officer has no public authority to demand a citizen to mow their lawn. Conditions where public authority can be applied by police officers also include scenarios where their actions are necessary to prevent a clear and present danger, much like the restrictions on free speech cited in the legal maxim about shouting fire in a crowded theater.
In the landmark case Terry v. Ohio, it was established that police could temporarily detain and search individuals if they have reasonable suspicion of criminal activity, without violating the Fourth Amendment. Yet, the boundaries of public authority are crossed when officers engage in practices like interrogating individuals without informing them of their rights, as this could undermine the protections afforded by the Fifth Amendment against self-incrimination. Terry stops and frisks are nuanced examples of public authority in action, which are lawful under specific circumstances but would become a form of abuse if conducted without proper justification.