Why don't phasers have a safety that scans the user? We see multiple times people's weapons being used against themselves, and Picard was nearly vaporized by his. So, why can't the phaser DNA scan (not full, just enough markers) to tell if the person holding it is Starfleet, and then disengage the safeties?

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    Starfleet personnel are routinely aided by locals, civilians, and even bystanders during crises on away missions. It would be tedious at best, and outright dangerous at worst, to make each of them go through a "registration" process before a wounded officer could say "take my rifle."
    – Nerrolken
    Commented Aug 3, 2015 at 16:47
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    Good idea! “PICARD: Worf, fire! [Worf pulls the trigger.] PHASER DISPLAY: Scanning target. Please wait. 2%... 3%... 4%... Commented Aug 3, 2015 at 17:58
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    “BORG: Your technological distinctiveness will be added to our own. Except for your phasers. They’re kinda slow, dude. [Assimilates everything.] Commented Aug 3, 2015 at 17:59
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    "DNA scan (...) to tell if the person holding it is Starfleet" - I had always thought (w.l.o.g.) human Starfleet personnel are just normal humans. However, if they are some kind of superhumans (which could be identified by DNA), that explains some of the things our heroes go through. Commented Aug 3, 2015 at 19:21
  • It's not an unusual concept in some sci-fi, but it's not usually DNA that is scanned, but something electronic -- the other person's similar smart-gun, or their combadge, or something similar, when detected in the targeting range, could disable the weapon from firing. Most fiction that has that function ALSO has at least one person in the group with the ability to deactivate it on a selective basis, or tell their own weapon to ignore it.
    – K-H-W
    Commented Aug 3, 2015 at 23:04

1 Answer 1


I think this is probably going to end up being opinion-based, since it's really a technological question about technology that doesn't exist, but I can offer a little perspective as a computer security AND a gun guy.

Stuff like this comes up with proposed gun regulation and with military tech, and it's referred to broadly as IFF - Identification, Friend or Foe. As the Wikipedia article points out:

The term is a misnomer, as IFF can only positively identify friendly targets, not hostile ones.

And there's the key - IFF can only identify friendlies, not identify hostiles. So now, consider the following scenarios:

  1. Friendly turns philosophically hostile.
  2. Friendly is bribed hostile.
  3. Friendly is coerced hostile.
  4. Friendly loses control and becomes dangerous (think munitions more than people).

Those are fairly down to earth possibilities. Consider these:

  1. DNA is spoofed to match friendly (this happens in the real world with IFF)
  2. Friendlies are affected somehow so that their friendly IFF signature doesn't register.

Some last points from other dangerous hobbies on why "safer is less careful":

  1. There's a table saw on the market right now that will stop (and destroy, incidentally) the blade if it comes in contact with flesh (it's measuring the eletrica potential of flesh - they use a hot dog to demo it). Do you think people will be more or less careful around that sawblade than a regular one?
  2. Blacksmiths don't wear gloves to protect their hands. The reason for this is that if you touch something super hot with a bare hand, you'll drop it, and have a little burn. If you touch it with a pair of gloves, by the time the heat registers through the glove, your glove is on fire, and will burn that hand AND the hand trying to pull the glove off with.

Weapons and dangerous tools are designed to accomplish a certain task, and at certain point, you just have to accept that they aren't 100% safe - if you push towards that 100% safety level, you AT LEAST compromise their effectiveness, and at worst you make them even more dangerous, or more likely to be operated in an unsafe fashion.

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    For the record, the point of the sawstop is that it's a last resort. Since it costs hundreds of dollars to reset it, there's still a reason not to activate it. There really are no safety implications to people being "less careful" around it, since that's the point of the mechanism.
    – Valorum
    Commented Aug 3, 2015 at 19:33
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    Also worth adding to your list: hacking. An enemy could hack their way into being able to use the device, or worse, could hack the device to reject the users who should have permission. It would be just like a Romulan to de-activate a Federation squad's weapons right before the battle...
    – Nerrolken
    Commented Aug 3, 2015 at 21:31
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    I saw a DEF CON talk about a "smart gun" that would not fire unless it was in close proximity to a matching watch using some simple challenge-response protocol. Naturally, it turned out that not only was bypassing the check trivial, but proper operation of the firearm could be prevented by jamming it. So you can imagine a third possibility beyond "DNA spoofing": jamming the DNA scan itself so the phaser cannot get a positive identification and refuses to fire.
    – forest
    Commented Feb 28, 2021 at 4:26

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