I'm pretty sure Starfleet Regulation 66718: Paragraph 2: sub paragraph 34, indicates that Starfleet officers are not permitted to 'run around the ship with a loaded Phaser' without the expressly given permission of the security chief and only when a Yellow or Red Alert status has been declared by the commanding officer of the vessel.
'If the Apocalypse starts, beep me!' - Buffy Summers
'The sky's the limit.....' Jean-Luc Picard, 'All Good Things'
courtesy of Saquist