* AcceptableTargets: Any relatively harmless modern subculture that seems scary or dangerous to the general public or the target audience. See the InternetBackdraft example below.
** Gamers and gaming in "Hitting for the Cycle". For the love of all that is holy...
** Subverted in, of all places, the episode that dealt with ''actual'' circus freaks. The freaks are the most sympathetic characters in the episode, are not portrayed as pathetic or as people to be looked down on, and the killer [[spoiler:turns out to be by far the most "normal" out of all the suspects]].
** In at least three different instances, sex offenders were "outed" to their neighbors (and thus had their lives ruined by the [=CSIs=]) despite fact that in all three cases, the people involved had a) served their jail time and were now leading clean, unoffensive lives b) were only tangentally involved in the cases, if even that, and c) police investigators aren't supposed to give out information on suspects to the general public '''''anyway''''' regardless of what that information is, as doing so until a conviction occurs is a serious civil rights violation.
* AndThereWasMuchRejoicing: [[spoiler: Music/JustinBieber's character's death]] brought some ''real life'' rejoicing.
** When Grissom returned in a guest spot in Season 11, and the rumours that he'll be back in Season 12 for Catherine's exit. Although he didn't return, the PTBs feared it would take too much focus off Catherine.
* AndYouThoughtItWouldFail: {{ABC}} turned the series down with the excuse of it being, "[[ViewersAreMorons Too confusing for the average viewer]]". Of course, it became a smash hit and the start of the ForensicDrama genre.
* {{Anvilicious}}: The episode centered around internet bullying, though possibly a case where this [[SomeAnvilsNeedToBeDropped needs to be brought to the public eye]] but it does get a bit egregious when Nick basically tries to say anyone who ever looked at the mocking videos, even if they did nothing about it or thought it was in bad taste, deserved to be put to the court system.
* BaseBreaker: Sara is either one of the most compelling and {{woobie}}ish characters on the show, or just plain crass and annoying.
** Ray Langston...either he was a great character or CreatorsPet and really overused and given too much to do for a CSI 1.
* BrokenBase: Dear Lord. Some fans insist the show JumpedTheShark after Season 5. Others say it happened when Grissom was shown in bed with Sara in the season 6 finale. Some say it didn't happen until Season 8/9 with [[spoiler: Warrick's death and Grissom leaving]]. Some declare Season 11 the worst due to it [[ArcFatigue dragging out]] the Ray/Haskell storyline. [[spoiler: Ray leaving and two new characters entering is only causing more divides in the fandom.]] Recent events in the (mostly off-screen) relationship between Sara and Grissom appear likely to cause even more division among fans.
* CompleteMonster:
** Mandy and Cameron Klinefeld from season 4's "Assume Nothing" put the "unholy" back in UnholyMatrimony. A married couple united by a shared sexual fetish for rape and murder, the pair operate by abducting other husbands and wives, sexually torturing the women while making the men watch, with the ultimate goal of forcing them to MercyKill the women they love. They promise the husbands they can go free if they do this, but [[ILied they're lying]].
** Season 12 ArcVillain Laura Gabriel is a ruthless arms smuggler and BigBadFriend to [[TheLancer Catherine Willows]]. Playing a meek and submissive wife to her [[CorruptCorporateExecutive sleazy private military firm head husband Mark]], she uses this false personality to deflect blame off her and onto him as she funnels his company's weapons to TheMafia and {{The Cartel}}s. When the investigation starts getting too close to the truth, she hires employees of the company to murder her own lawyer and all of his staff; following this, [[YouHaveOutlivedYourUsefulness she kills the assassins]] and burns their bodies beyond recognition in order to fake her own death and that of her right-hand man. She intended for an enraged Catherine to [[VigilanteExecution summarily execute her husband]], and also placed a contract on Catherine herself to clean up the last remaining loose end, not caring for her old friend in the slightest.
* CreatorsPet: Ray Langston. Many fans either dislike him or thinks he's SoOkayItsAverage, yet in his run he had three season finales, the 200th episode and two season long serial killer arcs dedicated to him and his problems.
* CriticalResearchFailure: "Fur and Loathing" makes some gross exaggerations, misinterpretations and otherwise ''wrong'' turns in the FurryFandom.
* EnsembleDarkhorse: Greg and Hodges in earlier seasons; when they were promoted to main characters the other lab rats got the same treatment, with Archie and Mandy in particular being well loved by the fans.
* TheFireflyEffect: Character example. Sofia Curtis, played by Louise Lombard. She was hardly developed, and only really had one episode focus on her (the episode "A Bullet Runs Through It"), but it seems the writers got bored with her. This resulted in Louise Lombard [[ScrewThisImOuttaHere quitting the series, and moving back to England.]]
* HarsherInHindsight (Or Foresight, considering there was at least 5 hours between the conclusion and the show's airing): An episode about a very troubled person shooting up the LVPD (3 dead [[spoiler: including the gunman, a teenager; additionally the person who manipulated him into shooting was arrested]], at least a dozen wounded) airs ''the same day'' a very troubled person [[http://www.chicagotribune.com/news/chi-fort-hood-shooting-20140403,0,2607630.story shoots up an army base]] (4 dead including the gunman, over a dozen wounded).
* HoYay: Nick and Greg. In fact, such a pairing has a large following, especially due to the subtext that occurs in their interactions.
* InternetBackdraft: Never mention the episode "Fur and Loathing" to FurryFandom.
* JumpedTheShark: Two words. Justin. Bieber.
** Although some people [[CatharsisFactor enjoyed seeing him commit suicide on-screen.]]
** Some fans said it jumped when Grissom left.
** The issues in Grissom and Sara's relationship and the recent revelation about them have fans yelling it again.
* MemeticMutation: Grissom literally GrowingTheBeard. It's arguably second to Chuck Norris.
* {{Padding}}: The video games REALLY make you work to match fingerprints, DNA, and chemical samples.
* RetroactiveRecognition: A lot of secondary guest stars eventually found fame after their appearance on ''{{Series/CSI}}''. [[Series/TheOfficeUS Rainn Wilson and John Krasinski]] both had guest spots before their own hit show, with Wilson having a memorable bit in one of the more popular episodes ("The Strip Strangler") as a possible suspect. And ''Series/{{CSI NY}}'' 's Carmine Giovinazzo was a guest star on here before becoming a regular on the spinoff series. But, WordOfGod says the guest appearance wasn't an influence in casting him. A.J. Buckley, also from CSI NY, appeared on this show before becoming a regular on the spinoff.
** [[Film/{{Avatar}} Norm]] was the killer (sort of) in "Dog Eat Dog." The best example, however, is Eric Stonestreet as Ronnie Litra, the lab's questioned documents expert, who [[ChuckCunninghamSyndrome disappeared without explanation]] around the middle of Season 4... and is now quite famous as [[ModernFamily Cameron]].
* TheScrappy: Kevin, "Hitting for the Cycle". How on earth did he get hired? [[spoiler: He bites the dust at the end of the episode.]]
* SeasonalRot: Happens with nearly any LongRunner. While not ''bad'' in its later years, the show received a lot more press, ratings, and critical acclaim in its first few seasons (even earning a few Emmy nominations). One could make a case with show growing stale as early as Seasons 6/7, but it was likely Grissom's departure in Season 9 that really accelerated things.
* UncannyValley: Somewhat discussed in "Lab Rats". See its quote under AllPsychologyIsFreudian on the main page.
* TheWoobie: All of the main cast have their moments, but Nick, Greg and arguably Sara get hit with it the most.