The Real Reason Gibbs Has Rules On NCIS

As a wise man once said, "A man got to have a code." NCIS's Special Agent Leroy Jethro Gibbs (Mark Harmon) operates on the other side of the thin blue line from that man (The Wire's Omar Little, for those keeping score at home), but he also lives and works by a set of personalized laws.

Known to his team as Gibbs' rules, these dictums have become as much a part of Gibbs' persona as his stern countenance, coffee addiction, and slaps to the back of the head that somehow haven't yet been reported to HR. (Possibly on account of alternate Rule #1: Never screw over your partner.)

From the very first episode, way back in 2003, we see Gibbs trying to instill these rules in his team. It worked: characters often call each other out for violations (including Gibbs), and make decisions based on Gibbs' guidance. That said, all of them — Gibbs included — have broken the rules at some point.

Rule #12: "Never date a coworker" has been especially hard at times. And despite Elton John's assertions about a certain word being the hardest to say, Gibbs has stumbled multiple times on Rule #6: "Never say you're sorry, it's a sign of weakness." But it was Rule #10: "Never get personally involved with a case" that proved so difficult to follow that Gibbs officially expunged it from the list in season 16.

Where did the rules come from — and how many are there? Here's the real reason Gibbs has rules on NCIS.

If you only joined the NCIS party recently, you know about Gibbs' rules — but you may not know their origin story. Originally, it's hinted that Gibbs picked up the idea of creating a code to live by from his stint as a Marine; the military is famous for being a rule-loving bunch. However, in season 6, we find out that he actually got the idea from his first wife Shannon, who was murdered. (Shannon is played by Aviva Baumann in that episode and by Darby Stanchfield of the hit Netflix series Locke & Key in the rest of the series — which may be why Shannon Gibbs from NCIS looks so familiar.)

At their first meeting, Shannon tells Gibbs, "Everyone needs a code they can live by," citing her own rule: Never date a lumberjack. We later find out that Gibbs actually keeps a box with his rules written out on slips: he literally sets fire to now-defunct Rule #10.

The connection to Shannon explains why Gibbs is so secretive about how he came by his rules. The character is notoriously cagey about his previous domestic life; we don't even find out about Shannon and their daughter until the end of season three. Having Gibbs live by rules inspired by his dead wife — and pass them on to the next generation of NCIS investigators — keeps Shannon's influence alive in the show, and reminds us that beneath his gruff exterior, Gibbs is a widower with a broken heart.

At the moment, we don't know all of Gibbs' rules — or even how many there are. For example, Gibbs tells Ziva (Cote de Pablo) that he has about 50 that he wants to teach her. However, since then, we've heard Rule #62: "Always give somebody space when they get off the elevator," Rule #69: "Never trust a woman who doesn't trust her man," Rule #70: "Keep digging until you hit bottom" (that might be a McGee addition), and Rule #73: "Never meet your heroes." There's even a Rule #99: "Never tell Gibbs he's being audited."

NCIS has been going for long enough that someone born in the year that the first episode aired is old enough to drive. The writers need something to keep the curiosity alive in viewers, and teasing out these rules is a chance to do that in a way that feels exciting but also like an in-joke. The finale of season seven may be the clearest example of the NCIS creators using the mystique around the rules to woo viewers. Titled "Rule Fifty-One," the episode saw Gibbs create a new rule: "Sometimes you're wrong."

The man who plays Gibbs has another take. In 2012, Harmon told TV Equals, "I actually find Gibbs' rules interesting, and his moral structure or compass... maybe rules aren't a bad thing for people. Certainly some of the ones that he's spouted over the years here, they make you think a little bit." Sure, you might find inspiration — but you'll definitely keep tuning in.