Understanding all of Gibbs' rules in NCIS and what they mean is essential to knowing Leroy Jethro Gibbs. Mark Harmon played the character for nearly two decades on the series, using the rules to help establish his character and how the Naval Criminal Investigative Service operated. Gibbs' rules kick off the series in NCIS season 1, episode 1, "Yankee White," one of the best episodes of NCIS. The Special Agent-in-Charge uses them to give Sasha Alexander's newly minted Caitlin "Kate" Todd the lay of the land when investigating aboard Air Force One.
Gibbs' rules were necessary for the original Major Case Response Team leader in NCIS. The rules were the quickest way for Gibbs to relay critical information in the shortest time. While many of Gibbs' rules dictate crime scene management, later rules feel more personal. In NCIS season 3, Gibbs said he had about 50 rules, but more of Gibbs' rules were revealed until Mark Harmon exited NCIS in season 19. The list expanded into about 100 rules, but it must be completed. Some of Gibbs' rules still need to be discovered since Gibbs didn't divulge his code chronologically.
37Rule #1
Never Let Suspects Stay Together.
Gibbs revealed Rule #1, "Never let suspects stay together," in NCIS season 1, episode 1, "Yankee White." Gibbs stated the rule to Kate aboard Air Force One after she had kept a group of airplane staff for questioning in the same room. Gibbs has an alternative Rule #1, "Never screw over your partner," which Jenny Shephard recited to him in season 4, episode 14, "Blowback."
The NCIS franchise acknowledged two Rule #1s in NCIS season 8, episode 11, "Ships in the Night." When Gibbs broke Rule #1, "Never let suspects stay together," to get a confession, McGee clarified that there was more than one primary rule. NCIS executive producer Shane Brennan revealed that it's because three of the regulations Gibbs has are from Mike Franks, and the rest are his own, which is why there are two Rule #1s and Rule #3s.
36Rule #2
Always Wear Gloves At A Crime Scene.
Gibbs also revealed Rule #2, "Always Wear Gloves At A Crime Scene," to Caitlin Todd in "Yankee White" aboard Air Force One. After someone poisoned an aid to the president on his private aircraft, Kate became entangled in the NCIS investigation because she was with the Secret Service. While Gibbs initially told Kate the rules so that she could cooperate in the investigation, the knowledge came in handy when Kate subsequently joined Gibbs' team after she was fired from the Secret Service.
35Rule #3
Don't Believe What You're Told. Double Check.
Rule #3, "Don't believe what you're told. Double check," is the final rule Gibbs imparts to Kate during the opening episode of NCIS. The first three rules in "Yankee White" helped establish the ethos of the entire NCIS franchise. Tony also revealed an alternative Rule #3, "Never be unreachable," to Ziva in NCIS season 3, episode 13, "Deception."
34Rule #4
The Best Way To Keep A Secret? Keep It To Yourself.
Jenny Shephard recited Rule #4, "The Best Way To Keep A Secret? Keep It To Yourself," to Gibbs in NCIS season 4, episode 11, "Blowback." The director also gave two corollaries to the rule: "The second-best way to keep a secret, tell one person," and "There is no third best." The rule evoked a powerful delivery from Shephard, who had known Gibbs personally and had a more intimate understanding of his rules.
33Rule #5
You Don't Waste Good.
Gibbs revealed Rule #5, "Don't waste good," in NCIS season 8, episode 22, "Baltimore." The episode explored Tony DiNozzo's background as a Baltimore homicide detective and revealed how Gibbs and Tony began working together at NCIS. Gibbs' precursor to revealing Rule #5 to DiNozzo was telling him, "You're Good." Tony was Gibbs' second-in-command until Michael Weatherly left NCIS in season 3.
32Rule #6
Never Say You're Sorry.
Gibbs repeated Rule #6 throughout the series but gave it an official number in NCIS season 7, episode 12, "Flesh and Blood." Gibbs says "Never say you're sorry" to his protégé, Anthony DiNozzo, who was familiar with Gibbs' rules. In NCIS season 3, episode 23, "Hiatus Part I," Tony explained to Shephard that Gibbs took the signature rule from "The Duke Himself," meaning John Wayne.
31Rule #7
Always Be Specific When You Lie.
Custom Image by Diana Acuña
Gibbs said Rule #7, "Always be specific when you lie," in NCIS season 1, episode 23, "Reveille." He recited the rule to Kate when she came to meet him for coffee near the end of the series' freshman season. The rule instructed Gibbs' agents to be thorough when crafting their covers.
30Rule #8
Never Take Anything For Granted.
Abby revealed Rule #8 in NCIS season 3, episode 10, "Probie." After Abby told McGee that the eighth rule of the code would save him, Ziva, Tony, and McGee tried to guess the rule. The moment signified that remembering and maintaining Gibbs' rules is just as important to the team as it is to Gibbs. An alternative Rule #3 is given in NCIS season 9, episode 21, "Rekindled,": "Never assume."
29Rule #9
Never Go Anywhere Without A Knife.
Rule #9, "Never go anywhere without a knife," came up a few times throughout the 21 seasons of NCIS. The rule was paramount for Gibbs since he had been a Gunnery Sergeant in the Marine Corps. Gibbs knew the value of self-defense first-hand and instilled in his team to have multiple ways to protect themselves.
28Rule #10
Never Get Personally Involved On A Case.
Tony established Gibbs' Rule #10, "Never get personally involved on a case," in NCIS season 7, episode 21, "Obsession." In the episode, Tony admitted to Gibbs that he broke the rule, again, to which Gibbs agreed, saying, "That's the rule I've always had the most trouble with." Moreover, in NCIS season 16, episode 13, "She," Gibbs does away with the rule by physically burning it in his fireplace.
27Rule #11
When the job is done, walk away.
Gibbs' Rule #11, "When the job is done, walk away," comes up in NCIS season 6, episode 24, "Semper Fidelis." Gibbs reminds Tony of the rule at the end of a case, and the protégé quotes it back to Gibbs. The rule is important for the characters as NCIS agents since the cases can be physically and mentally exhaustive. It's essential that the characters can separate from their work at the end of the day.
26Rule #12
Never Date A Coworker.
Gibbs' Rule #12, "Never date a coworker," came up in NCIS season 1, episode 15, "Enigma." Special Agent Kate Todd was still with NCIS then, and she reminded Tony of the rule while they were sitting in the bullpen. The series narrowly avoids the rule, with NCIS playing out will-they-won't-they relationships between its leading characters to avoid workplace gray areas, like Tony and Ziva's NCIS romance.
25Rule #13
Never, Ever Involve A Lawyer.
Gibbs' Rule #13. "Never, ever involve a lawyer" was initially recited by Tony in NCIS season 6, episode 7, "Collateral Damage." Tony recited the rule and followed it up by saying that Gibbs has seven rules involving lawyers and that none "are pretty," but #13 is the "umbrella rule." Gibbs' cautious nature toward lawyers is rooted in three divorces that gave the Special Agent-in-Charge plenty of experience with legal professionals. The rule is revisited in NCIS season 7, episode 24, "Rule Fifty-One."
24Rule #14
Bend The Line, Don't Break It.
Gibbs' Rule #14, "Bend the line, don't break it," came up in NCIS season 11, episode 4, "Anonymous Was A Woman." The rule was emblematic of Gibbs' entire approach to police work. Gibbs often worked outside the lines to follow the spirit of the law rather than its letter, but ultimately, he was a professional who held down a position at NCIS for decades.
23Rule #15
Always Work As A Team.
Gibbs' Rule #15 was another installment of the Special Agent-in-Charge's code remembered and quoted by NCIS Director Jennifer Shephard. In NCIS season 5, episode 5, "Leap of Faith," Jenny asked Gibbs, "Wasn't Gibbs' rule number 15 always work as a team?" Jenny and Gibbs were once intimately involved, so her knowing the rules had another meaning – he taught them to her in the 1990s when they were partners.
22Rule #16
If Someone Thinks They Have The Upper-Hand… Break It!
Gibbs' Rule #16, "If someone thinks they have the upper-hand… break it!" came up in NCIS season 8, episode 24, "Pyramid. It's not surprising that Gibbs has this rule in his repertoire, since he's a person who likes to have the upper hand (and usually does). NCIS' premise, for many years, relied on Gibbs' ability to stay one step ahead of almost anyone.
21Rule #18
It's Better To Seek Forgiveness Than Ask Permission.
Director Jennifer Shephard revealed Gibbs' Rule #18, "It's better to seek forgiveness than ask permission," in NCIS season 3, episode 4, "Silver War." Shephard and Gibbs have known a thing or two about forgiveness over the years since they were once in an intimate relationship. When Jenny revealed the rule, Gibbs responded, "Oh, that's real nice, using the rules I taught you against me."
20Rule #20
Always Look Under.
Gibbs' Rule #20, "Always look under," was revealed in NCIS season 12, episode 17, "The Artful Dodger." Rule #20 is a practical guideline for NCIS agents, who need to investigate a crime scene for the sake of their own lives. For instance, there has been a bomb strapped to the underside of a car that easily could have been missed, but by "looking under" lives were saved.
19Rule #22
Never, Ever Both Gibbs In Interrogation.
Gibbs' Rule #22, "Never, ever both Gibbs in interrogation," appeared in NCIS season 4, episode 10, "Smoked." Ziva wanted to talk to Gibbs, but Tony recited the rule to warn Ziva of a line they should not cross. Bothering Gibbs during an interrogation or interfering otherwise is treated as a sensitive matter throughout the series.
18Rule #23
Never Mess With A Marine's Coffee If You Want To Live.
"Never mess with a Marine's coffee if you want to live," Gibbs' Rule #23, was introduced in NCIS season 2, episode 9, "Forced Entry." The rule, which helped to regulate the Marine and Special Agent-in-Charge's caffeine, came up early out of necessity. A black coffee a day (or several) from his favorite shop fueled Gibbs' police work for years.
17Rule #27
Two Ways To Follow. First Way, They Never Notice You. Second Way, They Only Notice You.
NCIS season 7, episode 15, "Jack Knife," established Gibbs' Rule #27: "Two ways to follow. First way, they never notice you. Second way, they only notice you." The team was about to embark on a stealth mission and Gibbs, McGee, and Ziva took turns reciting parts of the quote to mentally prepare. The rule was revisited later in the same season, in episode 24, "Rule Fifty-One," which honed in on Gibbs' core rules.
16Rule #28
When You Need Help, Ask.
Gibbs' Rule #28, "When you need help, ask," appeared in NCIS season 13, episode 10, "Blood Brothers." Gibbs recited the rule to Eleanor Bishop as they sat on her patio after he shared Thanksgiving dinner with her family. Ellie was processing her divorce from Jake, and Gibbs reminded her of the rule, encouraging her to discuss her problems.
15Rule #35
Always Watch The Watchers.
NCIS season 8, episode 22, "Baltimore" established Gibbs' Rule #35, "Always watch the watchers." The episode centered on Tony's background as a Baltimore homicide detective and his relationship with his former partner. When Abby asked Gibbs how he uncovered a helpful piece of evidence, he reminded her and McGee of Rule #35, which emphasized staying one step.
14Rule #36
If It Feels Like You're Being Played, You Probably Are.
"If it feels like you're being played, you probably are," comes up in NCIS season 9, episode 1, "The Nature of the Beast." Tony recited the rule to make a point, showing how much Tony respected his leader's code of values. Rule #36 encourages trusting one's instincts, along the same lines as, "If it seems too good to be true, it probably is."
13Rule #38
Your Case, Your Lead.
Gibbs recited Rule #38, "Your case, your lead," to Tony in NCIS season 6, episode 16, "Bounce." Gibbs used the quote to remind Tony of his agency in an investigation. Tony similarly used the rule, reciting it to Abby to remind her that she could take the lead. Evoking Rule #38 is an easy way to remind someone that they can take the lead, especially when it's something they have authority over.
12Rule #39
There Is No Such Thing As A Coincidence.
Gibbs' Rule #39, "There's no such thing as a coincidence," comes up in NCIS season 7, episode 21, "Obsession." McGee typed the rule on his typewriter as he worked on his personal book project, as McGee maintained another career as an author. The rule is simple yet one of the more nuanced guidelines in Gibbs' bag.
11Rule #40
If It Seems Someone Is Out To Get You, They Are.
Abby recited Gibbs' Rule #40 in NCIS season 7, episode 22, "Borderland." Gibbs and Abby were in Gibbs' basement when he said the number aloud, prompting Abby to recite the rule back to him. The rule was an easy way for Gibbs to remind someone to watch their back and trust their gut. It was significant that Gibbs reminded Abby of the rule, since he protected her like a daughter, despite Mark Harmon being the reason Pauley Perrette left NCIS and retired from acting .
10Rule #42
Don't Ever Accept An Apology From Someone That Just Sucker-Punched You.
Gibbs recited Rule #42, "Don't ever accept an apology from someone who just sucker-punched you," in NCIS season 9, episode 16, "Psych Out." The episode was one of a few featuring Jamie Lee Curtis' NCIS character , Dr. Samantha Ryan. It's likely that Gibbs developed this rule out of necessity, as his job involved a lot of communication that could resort to violence.
9Rule #44
First Things First, Hide Women And Children.
In NCIS season 7, episode 23, "Patriot Down," Gibbs established Rule #44: "First things first, hide women and children." This rule is essential to Gibbs' character, as he is a fierce protector of everyone in his life, especially women and children. Rule #44 is especially meaningful considering what happened to Gibbs' wife and daughter in NCIS .
8Rule #45
Clean Up Your Own Mess.
In NCIS season 7, episode 24, "Rule Fifty-One," Gibbs established Rule #45: Clean up your own mess. In the episode, Gibbs said, "Left a mess I've got to clean up," and Tony commented that it was basically Rule #45 . Gibbs was no stranger to cleaning up messes, and took accountability when he needed to, making Rule #45 a no-brainer.
7Rule #51
Sometimes – You're Wrong!
Gibbs wrote Rule #51, "Sometimes – you're wrong!" in NCIS season 7, episode 24, "Rule Fifty-One," which derived its title from the rule and focused on Gibbs' code of ethics. In the episode, Gibbs was looking through his box of rules when he officially penned it on the back of another scrap of paper. The rule-centered episode was the NCIS season 7 finale.
6Rule #62
Always Give People Space When They Get Off An Elevator.
Abby recited Rule #62 to Gibbs in NCIS season 11, episode 13, "Double Back." Gibbs' Rule #62, "Always give people space when they get off an elevator," was an essential premise at NCIS Headquarters. The elevator was the main hub for people arriving and departing the bullpen, and as a main source of traffic, it was often a chaotic and hectic space.
5Rule #69
Never Trust A Woman Who Doesn't Trust Her Man.
It was fitting when Rule #69 came up in NCIS season 9, episode 7, "Devil's Triangle." The episode centered on Diane Sterling, the ex-wife of both Gibbs and supporting NCIS character Tobias Fornell . The quote meant that if a person doesn't trust their partner, then they probably aren't very trustworthy themselves.
4Rule #72
Always Be Open To New Things.
Gibbs' Rule #72 was revealed on NCIS : Hawai'i season 1, episode 13, "Spies Part II." It was fitting to reveal the quote on the Island-themed spinoff, since the series itself was a new endeavor for the NCIS franchise. Gibbs' rule carrying over to its spinoff series displayed the expanse of Gibbs' influence.
3Rule #73
Never Meet Your Heroes.
NCIS season 16, episode 7, "A Thousand Words," revealed Gibbs' Rule #73: "Never meet your heroes." The quote meant that sometimes, when a person meets their hero, that hero can be disappointing, since a person can build them up to be more than they are. Gibbs' Rule #73 symbolizes how important controlling your mental perception is to Jethro Gibbs.
2Rule #91
When You Decide To Walk Away, Don't Look Back.
Gibbs and Ellie bond over Rule #91, "When you decide to walk away, don't look back," in NCIS season 18, episode 16, "Rule 91." The title of the episode is based on Rule #91, showcasing its significance to Gibbs and his core values. After leaving the Marine Corps, losing his family, and maintaining multiple ex-wives, Gibbs knows the importance of walking away with dedication more than anyone.
