What must a Coast Guard boarding officer display to signify their authority?

A Coast Guard boarding officer must display a badge and other official identification to signify their authority. This requirement is critical as it establishes the officer’s legitimacy and serves to both inform and reassure the individuals on the vessel that they are engaging with an official representative of the Coast Guard. The badge acts as a clear symbol of authority, while other forms of official identification can include credentials or documentation that further identify the officer's role and the breadth of their powers during the boarding process.

The combination of a badge with official identification helps prevent misrepresentation and ensures that those being boarded understand the legal basis for the boarding, which is essential in maintaining order and compliance during the encounter. This practice upholds the professionalism and integrity of the Coast Guard while assuring compliance with domestic and international laws.

In contrast, the other options are less appropriate. A firearm and a Coast Guard flag do not serve as direct evidence of authority in the same way official identification does. A written warrant from a judge is typically not necessary for routine boardings, as the Coast Guard has statutory authority to conduct such inspections without one. An identification card alone lacks the comprehensive assurance provided by a badge in conjunction with other forms of identification.