Understanding all of Gibbs' rules inNCISand 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 inNCISseason 1, episode 1, “Yankee White,” one of thebest episodes ofNCIS.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 necessaryfor theoriginal Major Case Response Team leader inNCIS. 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. InNCISseason 3, Gibbs said he had about 50 rules, but more of Gibbs' rules were revealed untilMark Harmon exitedNCISin 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,“inNCISseason 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.”
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TheNCISfranchise acknowledged two Rule #1s inNCISseason 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.NCISexecutive 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 ofNCIS.The first three rules in “Yankee White” helped establish the ethos of the entireNCISfranchise.Tony also revealed an alternative Rule #3,“Never be unreachable,“to Ziva inNCISseason 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 inNCISseason 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,“inNCISseason 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 atNCIS.Gibbs' precursor to revealing Rule #5 to DiNozzo was telling him,“You’re Good.“Tony was Gibbs' second-in-command untilMichael Weatherly leftNCISin season 3.
32Rule #6
Never Say You’re Sorry.
Gibbs repeated Rule #6 throughout the series but gave it an official number inNCISseason 7, episode 12, “Flesh and Blood.” Gibbs says"Never say you’re sorry"to his protégé, Anthony DiNozzo, who was familiar with Gibbs' rules. InNCISseason 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.
Gibbs said Rule #7,“Always be specific when you lie,“inNCISseason 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 inNCISseason 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 inNCISseason 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 throughoutthe 21 seasons ofNCIS. 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,“inNCISseason 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, inNCISseason 16, episode 13, “She,” Gibbs does away with the rule by physically burning it in his fireplace.
