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In Speculative Fiction, as in Real Life, technology is designed with certain unquestioned assumptions. The user has the normal number of appendages. The user is within a certain generous range of sizes. The user can withstand so many G's of acceleration. The user can shoot lightning from her hands, or commune telepathically with computers...just like everyone else in the builder's species.

In certain settings, Finagle's Law ensures these assumptions will cause disaster. Sure, sometimes it's a bonus, or even a built-in feature, that the alien saboteurs can't use the Artifact of Doom properly, but usually it's just a pain.

If a piece of technology only works for one specific user, that's Loyal Phlebotinum.

Examples of Operator Incompatibility include:


  • In District 9, alien weapons can only be used by those with the alien's arm, presumably due to some sort of DNA compatibility. Then, of course, the protagonist ultimately gets an alien appendage and fires at will.
  • In the movie Judge Dredd, the fact that a Judge's weapon can only be used by that particular Judge or someone sharing that Judge's DNA becomes a plot point.
    • Same for the comic, only they exploded and can tell if a clone sibling is using it since in the comics clone Judges are common.
  • In The Adventures of Buckaroo Banzai Across the Eighth Dimension, Buckaroo gets confused at the climax when trying to fly the Red Lectroid Thermapod because its controls are, among other things, designed to be operated partially by the pilot's bare (and presumably prehensile) feet. He therefore has to turn control of the ship over to the Black Lectroid John Parker, who unfortunately "failed driving school."
  • In Monsters vs. Aliens, the alien is octopus-like, and as a result his ship is controlled with what is essentially a DDR pad. Dr. Cockroach is still capable of using it though, albeit with some difficulty.

Live Action Television

  • A lot of tech in Stargate can only be operated by someone with the ATA (Ancient Technology Activation) gene. Luckily a procedure is developed that can give most people this trait, though those blessed by the plot are still inexplicably better at it.
    • As well the Goa'uld hand devices, healing and ribbon, only usable by someone who has or has had a Goa'uld symbiote.
    • Also, a lot of technology is created so that the Goa'uld can't use it. Whether or not they're problematic for Jaffa such as Teal'c or ex-hosts such as Carter varies.
  • Occurs in Farscape when anyone other than D'Argo tries to operate Lo'la. The ship requires D'Argo's DNA to function so it's...messy for someone else to use it.
  • Stairs were impossible for Daleks to use until they gained levitation technology. QI speculates that ramps are a Dalek conspiracy.


  • In The Colors of Space, by Marion Zimmer Bradley, humans need to be in stasis to use the FTL drive. Or so the aliens who invented the drive claimed.
    • In Bradley's The Heritage of Hastur, the Sword of Hastur is protected by two force fields. Only a telepath (there are many on Darkover, where the story takes place) can pass through the first one, but only a nontelepath can pass through the second one.
    • Noted in The Forbidden Tower: Terrans, who are usually right-handed, often have trouble using implements designed by/for Darkovans, who are usually left-handed. (Note related entry in "Real Life" section.)
  • In one Animorphs book, our heroes steal a Bug fighter that is usually piloted by a Taxxon (a really, really big centipede with maybe six or eight arms), and is here piloted by an Andalite with two arms. Then they learn the ship was designed with a mutant Taxxon in mind, one with "twice the usual amount of appendages". They manage to fly it perfectly though.
  • In the Liaden Universe, Val Con, a guy who's around 5'5, tries to operate a spaceship designed for a larger species of human. He gets seriously injured from this.
  • One of the characters in Harry Turtledove's Worldwar books is Kassquit, a human woman raised by the alien, lizardlike Race. She must wear artificial "fingerclaws" to be able to use the Race's computers.
  • The My Teacher Is an Alien series involves thousands of alien species living peacefully on one massive space station. This leads to some rather complex issues--for example, when the human protagonist first needs to use a bathroom he has to answer a series of rather personal questions to the computer, causing serious discomfort before he finds a toilet that will actually work for his anatomy.
  • Similar to the situation in The Colors of Space, the Tyr in C S Friedman's The Madness Season claim that FTL travel can only be performed by them because the method that they use causes a state of absolute terror for any other living thing in hyperspace. It is later uncovered that there is more than one method of FTL travel, but the Tyr suppressed those in order to maintain control of the galaxy.
  • In Anne Mason's The Stolen Law, Vallusians have six fingers on each hand. This leaves our human protagonist unable to work the gun they want her to train with; more seriously, when an important piece of technology is sabotaged, it reveals the existence of a Vallusian traitor, as none of the other known races would have been capable of manipulating the necessary controls.
  • Averted in the novelization of The Last Starfighter', since the Gunstar is capable of detecting the species of its pilot and modifying its cockpit and controls to match.

Tabletop RPG

  • Call of Cthulhu supplement Terror from the Stars. The Mi-Go have a Lightning Gun which they fire by grasping it and altering its electrical resistance. Humans who want to fire it have to clip one of its wires.
  • The Mechanoids from Palladium Books features telekinetic aliens. Their devices usually have the activation switches on the inside of the casing for a cleaner look. Human intruders who want to, say, use the elevator have to saw a hole and flip the switch manually.

Video Games

Web Comics

  • Celia's ill-conceived magic artifact in Order of the Stick requires a jolt of electricity to activate. Humans can't generate lightning at will? Since when?
    • On the flipside, an attempt to hang Belkar fails because he doesn't weigh enough to pull the noose taut enough to snap his neck.
  • A painless execution method, invented by a shapeshifting race in Starslip, requires 21 appendages, so humans can't use it. Female humans, anyway.
  • Subnormality's Sphinx can't watch movies in modern formats.
  • Freefall features a humanoid wolf with a wolf's snout, digitigrade legs, and black/white vision (Florence), a squid-thing wearing a humanoid environmental suit (Sam), a rotund robot of human-normal height (Helix), a giant construction robot (Sawtooth Rivergrinder), and assorted other semihumanoid robots (Dvorak, Tangent, and the robot tailor, for instance). This trope shows up often.

Real Life

  • CAPTCHAs, those things where you have to prove that you're a human and not a bot by entering the text from an image, have quite a difficult time distinguishing between bots and blind humans-- because speech synthesizers and Braille displays can't render images. For this reason, most CAPTCHA-protected sites include an option to have the characters spoken at you (which would benefit the blind but not bots).
  • A remarkable number of tools assume (often with dangerous consequences) that the user is right-handed.
    • This includes nearly all bullpup firearms (magazine well behind the trigger), as attempting to fire them left-handed will fling red-hot cartridge cases into the user's face or down their collar. Many newer bullpup weapons can be adjusted for left-handed firing in the field, but heaven help you if you then pick up the wrong rifle by mistake, or a right-handed soldier picks up yours.
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