Gibbs' Rules are an extensive series of guidelines that Leroy Jethro Gibbs lives by and teaches to the people he works closely with.
It was revealed in the last few minutes of the Season 6 episode, "Heartland" that Gibbs's rules originated from his first wife, Shannon Gibbs, where she told him at their first meeting that "Everyone needs a code they can live by." The only rule of Shannon's personal code that is quoted is either her first or third: "Never date a lumberjack." Years later, after their wedding, Gibbs began writing his rules down, keeping them in a small tin inside his home which was shown in the Season 7 finale episode, "Rule Fifty-One." Though he uses it often we almost never see the tin.
The knowledge of the rules's origins is left as a mystery to the people that Gibbs works with, though some of them do make concentrated efforts to find out. Anthony DiNozzo makes several attempts to find out who taught Gibbs the rules, though he has not yet met with any success. On one occasion, during the Season 1 episode, "Missing," DiNozzo quoted Rule Nine as a rule that "they teach you in the Marine Corps," but the Marine in question was unaware of what he was referring to.
At the beginning of her tenure with NCIS, during the Season 3 episode, "Silver War," Gibbs informed Ziva David that there were approximately fifty rules that were his job to teach her. Some years later, Gibbs added the "51" Rule to the tin he kept the rules in while according to Tony, seven of the rules directly concern lawyers, and that the eighth rule was inspired by a lawyer as revealed during the Season 6 episode, "Collateral Damage." Rule forty and above are not rules necessary for everyday life, they are for emergencies.
Rule 1: "Never let suspects stay together." - revealed in the Season 1 premiere episode, "Yankee White."
Rule 1: "Never screw over your partner." - revealed in the Season 4 episode, "Blowback." McGee also stated this rule to Ned Dorneget in "Need to Know." McGee also mentioned to Abigail Borin in "Ships in the Night" that rule number one has been taken twice, showing that he knows that there are two number one rules.
Rule 2: "Always wear gloves at a crime scene." - revealed in "Yankee White."
Rule 3: "Don't believe what you're told. Double check."- again revealed in "Yankee White."
Rule 3: "Never be unreachable" - revealed in the Season 3 episode, "Deception," although Gibbs has been known to be intentionally unreachable. The rule was shown in "Rule Fifty-One" in the background when Gibbs opens 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." - revealed in the Season 4 episode, "Blowback."
Rule 5: "You don't waste good." - revealed in the Season 8 episode, "Baltimore."
Rule 6: "Never say you're sorry. It's a sign of weakness." - This rule has been mentioned throughout the series, but it given a specific number until "Flesh and Blood." The rule is also a direct reference to John Wayne's catch phrase in She Wore A Yellow Ribbon (John Ford, Director). Wayne said: "Never apologize, mister, it's a sign of weakness." to subordinates in a military situation. DiNozzo notes the connection in "Hiatus Part 1." Mark Harmon's career has paralleled John Wayne's. They both were quarterback of their southern California college football team, both went into acting. (Harmon's father, Tom Harmon, was a Heisman Trophy winner and actor & announcer as well.) Note: This is continuously told to Tony, Ziva and Tim through a smack to the back of their heads.
Rule 7: "Always be specific when you lie." - revealed in the Season 1 finale episode, "Reveille."
Rule 9: "Never go anywhere without a knife." - revealed in the Season 1 episode, "One Shot, One Kill," although it's sometimes quoted as "Never leave home without a knife" or "Always carry a knife."
Rule 10: "Never get personally involved in a case." - revealed in the Season 7 episode, "Obsession" and again referenced by the new SECNAV Clayton Jarvis in the Season 9 premiere episode, "Nature of the Beast" as the number one rule in Washington politics.
Rule 11: "When the job is done, walk away." - revealed in the Season 6 episode, "Semper Fidelis."
Rule 12: "Never date a co-worker." - revealed in the Season 1 episode, "Enigma."
Rule 14: "Bend the line, don't break it." - revealed in "Anonymous was a Woman."
Rule 15: "Always work as a team." - revealed in "Leap of Faith."
Rule 16: "If someone thinks they have the upper hand, break it." - revealed in the Season 8 finale episode, "Pyramid."
Rule 18: "It's better to seek forgiveness than ask permission." - revealed in "Silver War."
Rule 22: "Never ever bother Gibbs in interrogation." - revealed in "Smoked."
Rule 23: "Never mess with a Marine's coffee... if you want to live."- revealed during "Forced Entry."
Rule 35: "Always watch the watchers."- revealed in "Baltimore."
Rule 36: "If you feel like you are being played, you probably are" - revealed in "Nature of the Beast."
Rule 38: "Your case, your lead."- revealed in "Bounce."
Rule 40: "If it seems like someone is out to get you, they are." - revealed in "Borderland."
Rule 42: "Never accept an apology from someone who just sucker punched you." - revealed in "Psych Out."
Rule 51: "Sometimes you're wrong." - Created by Gibbs in "Rule Fifty-One" by writing it on the back of the card containing Rule 13. It is unknown if his coworkers are aware of this rule.
Rule 69: "Never trust a woman who doesn't trust her man." - revealed in "Devil's Triangle."
- "Never date a woman that eats more than you do." - as said by Tony in "Singled Out."
- In my country, on my team, working my cases, my people don't bypass the chain of command"- revealed by Gibbs during a talk with Ziva in "Switch."
- The Unspoken Rule- as revealed by Franks- You do what you have to do for family- revealed in "Spider and the Fly."
- Don't work the system when you can work the people- revealed in "Hung Out to Dry."
- Don't stop checking and rechecking evidence until you are satisfied.
- If you want to find something, you follow it. (Said by Gibbs to Mike Franks in "Deliverance" with Gibbs adding that he learned that one from Mike).
- Besides Rule 13, Gibbs has 6 other rules involving lawyers, but, according to DiNozzo, "You only need to know number 13; it's the umbrella one."
- Never second guess yourself in a relationship and life.
- Abigail Borin, Gibbs' counterpart at CGIS, also has a set of rules. The only one currently known is her Rule #1: Never make excuses.
- McGee has formed his own set of rules. Only 1 is known:
- Rule #1 Never lie to Gibbs.
- When DiNozzo was in charge, he made a set of rules.
- Rule #1: Don't sit on the sidelines while your people are in trouble.
- Rule #3: Never underestimate your opponent- revealed in "Hiatus Part 1."
- Abby also has her own rules.
- Jimmy Palmer once had a rule.
- Jimmy's Rule #1: Pipettes can never be too clean.
Although Gibbs has his list of rules to live by, he does not always adhere to them. One example is Rule #3. When Gibbs does not wish to be reached, he has been known to leave his cell phone behind. Except that many believe that to be one of Frank's rules since there are two Rule #3's. The other being 'Don't believe what you're told. Double check,' which sounds more like Gibbs. Also, on the anniversary of his last marriage, he unplugged his home phone and dropped his cell phone in paint thinner after his ex-wife began harassing him with phone calls. Gibbs also admits that rule number 10 is the one that he has had the most "trouble with" in "Obsession."
Gibbs broke Rule #1 (Never let suspects stay together) in "Ships in the Night" in order to get a confession. This also occurred in "Caught on Tape," but the suspects turned out to be innocent. Additionally, Gibbs broke the rule in "A Man Walks into a Bar," but the suspects were only guilty of covering up suicide, not murder.
Gibbs broke rule #13 (Never involve a lawyer) in "Mother's Day." Gibbs's ex mother in law becomes a suspect in a murder of a Navy officer. Gibbs contact Allison Hart, a lawyer, to represent her.
Gibbs also broke Rule #12 with former NCIS Director and partner in Europe, Jenny Shepard. Jenny was Gibbs' probie in their Europe missions and became romantically involved, which was ended by Jenny so she could lead her own team in Madrid. Although, since the relationship ended badly, some people suspect that this rule was created because of this relationship.
Another exception that Gibbs sometimes makes concerns Rule #6. Though Gibbs constantly tells people around him to never apologize, that it is a sign of weakness, he himself has apologized on at least six occasions:
- To Caitlin Todd for being late to her funeral in "Kill Ari Part 2."
- To Donald Mallard following his return from Mexico in "Smoked."
- To Joann Fielding for not being able to protect Shannon Gibbs and Kelly Gibbs in "Mother's Day."
- To Abigail Sciuto for frightening her and not being able to tell her what she wants to hear in "Rule Fifty-One."
- To the victim's lover for her loss, although he originally believes that she was being selfish in "A Man Walks into a Bar."
- To Timothy McGee for not being with him when he was accused of shooting a cop in "Probie."
- To "The General" (Captain Wescott) in "Shell Shock Part 2" for making him face a former serviceman and teammate, in which the encounter went poorly. Gibbs said, "That was my bad," for making Westcott agree to the meeting.
Though not shown, in "Semper Fidelis" ICE Agent Julia Foster-Yates claims that Gibbs and Fornell apologized to her for accusing her of murdering a coworker. McGee is shocked at the idea that either of them would apologize.
Gibbs also almost never accepts an apology from someone, preferring to simply offer correction to whomever made an error in an attempt to teach a lesson. One exception to this aspect of the rule was when McGee apologized concerning the situation with his sister, Sarah in "Twisted Sister." Gibbs has also accepted some apologies because they are covered by rule #18: "It's better to seek forgiveness, than ask permission."
Also an apology isn't a sign of weakness if it's between friends, as Gibbs tells Dr. Mallard in "Smoked."
Although not strictly an exception, Gibbs did add a sort of corollary to Rule 39 concerning coincidences. In "Head Case," when Tony says, "We don't believe in coincidences around here," Gibbs added, "However, we do believe in bad luck."
Throughout the series, there have been two rules referenced as the first and third of Gibbs' rules. For some time, it was believed that the duplications were either continuity errors or that the list of rules was meant to be malleable. Eventually, however, Executive Producer Shane Brennan revealed that the duplication was actually intentional:
“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. When he joined NCIS, Mike Franks told him he didn't need dozens of different rules to be an agent... just three 'golden rules.' And this is why we have double ups on rules #1 and #3. Three of them are Gibbs' rules; three of them are Mike Franks’ rules. We are still to reveal the double-up on rule #2. And it's up to the fans to guess which of the rules were Mike Franks’ three golden rules and which were Gibbs'.” (Shane Brennan's explanation of the duplication of Rules #1 and #3.) In spite of this, however, Franks seems to know Gibbs' rules as well as anyone, as evidenced in the episode "Patriot Down" when Gibbs passed the message "Rule #44" (First things first: hide the women and children) to him through Camilla.
While most of the rules are for everyday use, Gibbs' rules 40-49 are considered emergency rules, to be invoked only in the most dire of circumstances. ("Rule Fifty-One") When Gibbs told Abby that rule 40 was in play, and Abby told Tony, he took it to mean that "something unspeakably bad is going down."