NCIS: Why Does Mark Harmon's Gibbs Tell People To Never Apologize?

Leroy Jethro Gibbs (Mark Harmon) abides by a strict list of rules on "NCIS," and he expects his team to do the same. For example, he's told his colleagues to always wear gloves at crime scenes and never let suspects stay together, both of which are common sense in their line of work. However, one rule is more prominent than most, and Gibbs borrowed it from a legendary Hollywood actor.

Throughout the series, Gibbs tells people never to apologize because doing so shows weakness. While this can be interpreted as another example of his stoic sensibilities, it also references John Wayne's character in "She Wore a Yellow Ribbon." The moment occurs in the scene where Wayne's Captain Nathan Brittles says, "Never apologize, mister, it's a sign of weakness." The connection to the movie is confirmed in "NCIS" Season 3's "Hiatus (Part One)" episode during a conversation between Anthony DiNozzo (Michael Weatherly) and Jenny Shepard (Lauren Holly), where the former confirms that it's a nod to "The Duke."

Gibbs previously enlisted in the military before joining the NCIS team, so it's hardly surprising that he looks up to an actor famous for playing soldiers and lawmen. That said, what does Mark Harmon think about his character's rules?

While Leroy Jethro Gibbs' rules are primarily rooted in common sense, some people might question his no-nonsense mindset as he doesn't leave the door open to debate. Furthermore, he has a habit of slapping people on the back of the head if they break one of his rules. Despite Gibbs' stubbornness and slap-happy attitude, however, Mark Harmon believes these edicts enhance his character.

"I think it's good to have some sort of moral compass or character, structure," Harmon told CBS (via Showbiz Cheatsheet). "And I think that's what Gibbs has. But whether I practice them or I have a favorite, you'll never know."

Moving forward, it remains to be seen if Gibbs will ever rejoin the team to enforce his rules all over again. Harmon left the show in Season 19, but Gibbs' "NCIS" return could still pay off, as the series' creators have revealed that the door is always open to him. Harmon also teased Gibbs' return ahead of Season 21, suggesting he's open to slapping more heads down the line.