Final answer:
Off-duty firearms carry requires a license, protected by the Second Amendment for individual self-defense at home, but state laws can impose location restrictions with associated penalties.
Step-by-step explanation:
The question concerns the legal requirements for off-duty firearms carry. Typically, a police officer or lawfully authorized individual may carry a handgun if they have obtained the necessary license, which, as noted in previous District of Columbia laws, could be a one-year license for handguns. The District of Columbia v. Heller (2008) case is a pivotal decision where the U.S. Supreme Court held that the Second Amendment protects an individual's right to possess a firearm for lawful purposes, such as self-defense within the home, and that the requirement for firearms to be kept nonfunctional in the home was unconstitutional. This ruling emphasizes the right to keep guns for self-defense, overruling the District's restrictions on the registration and functionality of handguns in the home.
Moreover, per state laws, there are often regulations in place that prohibit carrying firearms in certain public areas, and violations can lead to penalties. For example, state law can prescribe penalties for carrying weapons in public recreational property. However, in situations where police have a reasonable suspicion that a person is armed and dangerous, as established in Terry v. Ohio (1968), they have the authority to frisk the person without violating their Fourth Amendment rights.