Special Agent Leroy Jethro Gibbs lives his life by a set of rules that took root from the first day he met Shannon. Over time, Gibbs added to the rules. He instills these rules in everyone in his team. Of the fifty-one rules only twenty-three have been revealed.
- Rule 1: Never let suspects stay together. (Yankee White, 1.01)
- Rule 1: Never screw over your partner. (Blowback, 4.14)
- Rule 2: Always wear gloves at a crime scene. (Yankee White, 1.01)
- Rule 2: Unknown at this time
- Rule 3: Don’t believe what you’re told. Double check. (Yankee White, 1.01)
- Rule 3: Never be unreachable. (Deception, 3.13) ; (Rule Fifty-one, 7.24 in the background when opening the box)
- Rule 4: The best way to keep a secret? Keep it to yourself. Second best? Tell one other person – if you must. There is no third best. (Blowback, 4.14)
- Rule 6: Never apologize. It’s a sign of weakness. (Specifically mentioned in Flesh and Blood, 7.12)
- Rule 7: Always be specific when you lie. (Reveille, 1.23)
- Rule 8: Never take anything for granted. (Probie, 3.10)
- Rule 9: Never go anywhere without a knife. (One Shot, One Kill, 1.13 ; Missing, 1.20) Sometimes as “Never leave home without a knife.”
- Rule 10: Never get personally involved in a case (Obsession, 7.21)
- Rule 11: When the job is done, walk away. (Semper Fidelis, 6.24)
- Rule 12: Never date a coworker. (Enigma, 1.15)
- Rule 13: Never, ever involve a lawyer. (Rule Fifty-one, 7.24; Collateral Damage, 6.07)
- Rule 15: Always work as a team. (Leap of Faith, 5.05)
- Rule 18: It’s better to seek forgiveness than ask permission. (Silver War, 3.04)
- Rule 22: Never, ever bother Gibbs in interrogation. (Smoked, 4.10)
- Rule 23: Never mess with a Marine’s coffee if you want to live. (Forced Entry, 2.09)
- Rule 27: There are two ways to follow someone. — First way they never notice you. — Second way they only notice you. (Rule Fifty-one, 7.24; Jack Knife, 7.15)
- Rule 38: Your case, your lead. (Bounce, 6.16)
- Rule 39: There is no such thing as coincidence.(Obsession, 7.21)
- Rule 40: If it seems someone is out to get you, they are. (Borderland, 7.22)
- Rule 44: First things first, hide the women and children. (Rule Fifty-one, first mentioned in Patriot Down, 7.23)
- Rule 45: Clean up the mess that you make. (Rule Fifty-one, 7.24).
- Rule 51: Sometimes – You’re wrong (Rule Fifty-one, 7.24)
- Number not Revealed: In my country, on my team, working my cases, my people don’t bypass the chain of command. (Switch, 3.05)