Because there are 50 states with 50 sets of firearms statutes, the decision in the Smith case does not amount to a green light for officers to carry their firearms wherever they please. As the judge's comment makes clear, states can permit private entities to prohibit the possession of firearms on their private property. For example, South Dakota could enact a statute making it a misdemeanor to possess a firearm where prohibited by the property owner, with adequate notice (such as a sign prominently posted at all entrances to the property). Off-duty officers could then be prosecuted for carrying their handguns onto the property, because the federal law allows such a restriction.
Before traveling to another state where you intend to carry while off duty, do a little online research, or contact a law enforcement agency in your destination state and inquire about the local laws regulating firearms possession on private property. It's also important to be familiar with the federal statutory provisions that allow states to preclude possession of firearms by officers on government property or parks. Other provisions make the federal authority to carry inapplicable when an officer is under the influence of alcohol or drugs, or when an officer is subject to pending disciplinary action. Retired officers are subject to additional restrictions, as listed in the above mentioned 2004 Point of Law article.
Second Amendment Developments
Just a few weeks before the Sturgis roadhouse confrontation, the U.S. Supreme Court issued a landmark Second Amendment opinion, District of Columbia v. Heller. State and federal courts continue to litigate the application of that ruling to firearms violations.
DC v. Heller
Dick Heller was a resident of Washington, D.C., who wanted to keep firearms in his home for self-defense. DC laws prohibited handgun possession and required that any long guns kept in the home be locked or disassembled. Heller challenged those laws on constitutional grounds in federal court, eventually landing at the Supreme Court. The High Court ruled in Heller's favor, declaring that the DC bans violated the Second Amendment.
The Supreme Court held that the Second Amendment right "to keep and bear arms" is an individual right, not just a right of state militias. Historical precedent indicated that the chief reason for enactment of the Second Amendment was protection of a right to use firearms in defense of the home. Since the DC bans would thwart the ability of residents to readily defend themselves in their homes, they were held unconstitutional.