In Star Trek: The Next Generation there are multiple species who can, to various degrees, read the mind and/or emotions of other beings. This brings up a host of privacy concerns, and this question made me wonder if we've ever seen this being dealt with on-screen - either by the Federation as a whole, or by the individual species/groups.

Troi, for example, is a Counsellor and as such operates under confidentiality limitations in the course of her job. It would be considered both immoral and highly unprofessional for her to spill any of her patients secrets to others (in all but the most extreme circumstances).

Do we ever see a similar discussion of the ethics of information gained by telepathic means, in particular information the individual would like to keep hidden?

  • Deana's mother once says " The poor dears. Our style of complete honesty frightens them."
    – NKCampbell
    Aug 29, 2018 at 13:27
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    There's an episode where a half-betazoid hides his betazoid heritage and serves as a negotiator...I think. I vaguely recall that Troi had a problem with how he was leveraging his ability for gain in the way he was. And Troi's mother seemed quite fond of poking people with their private thoughts for her amusement, though she generally seemed to hold these to herself (for said amusement and leverage). Aug 29, 2018 at 13:31
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    @zibadawatimmy: “a half-betazoid hides his betazoid heritage and serves as a negotiator” — yup, The Price. Aug 29, 2018 at 14:10
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    @Paul D. Waite Technically Devinoni Ral was a quarter Betazoid. memory-alpha.wikia.com/wiki/Devinoni_Ral RAL: I am part Betazoid too. My mother was one half, I am one quarter. chakoteya.net/NextGen/156.htm Aug 29, 2018 at 14:48
  • @M.A.Golding Yes, but I am certain Paul has found the episode I was thinking of. I simply mis-remembered quarter-betazoid as half-betazoid. Aug 29, 2018 at 14:51

3 Answers 3


In TNG Violations we see Mind Rape by Ullians who are, by inference, not part of the Federation...

Although Picard says the Federation has no law against telepathic memory invasion, the Ullians do and the penalty is severe, even though the practice has been unheard of for centuries.

The situation resolved, Tarmin promises the assistance of Ullian physicians, but warns that no incidences of this form of rape have occurred in over 300 years, and these physicians might be somewhat out of practice. Tarmin himself is badly shaken by the thought that any Ullian, much less his own son, could have committed acts that have not been known since a dark time in Ullian history was resolved.

Picard notes that, although Earth experienced such times and is now peaceful, it is important for both Humans and Ullians to recognize that the seed of violence remains within all of them. To forget that is to risk allowing such a seed to grow and consume them, as it did Jev

This lack of a law appears to be in existence since TOS since a Vulcan mind meld is forced on Valeris in the moive The Undiscovered Country

In Star Trek VI: The Undiscovered Country, Spock forcefully used the technique on Valeris to discover information she had that could be used to prevent a war; Valeris began screaming just before Spock broke the connection.



In the TNG episode Tin Man we see a Betazoid (Tam Elbrum) who was "woke" to his telepathy at birth. As such, we see that, even though he is considerably gifted as a telepath, he also doesn't have an actual filter. What's odd is that he casually reads minds in ways that we see other Betazoids get negative reactions to, and yet nothing is ever said or done about it.

TROI: Well, in most Betazoids our telepathic gifts develop at adolescence.
PICARD: You mean you're not born reading minds?
TROI: No. Except for some reason that no one understands, occasionally a Betazoid child is born different.
PICARD: How different?
CRUSHER: Born with his telepathic abilities switched on.
TROI: Most Betazoids born like that never lead a normal life.
CRUSHER: The noise of other people's thoughts and feelings must be overwhelming, incomprehensible, especially to a child.
TROI: And painful. Early diagnosis and special training did help Tam adjust, but he has some problems.

And later (emphasis mine)

TAM: How're things in the land of the living?
TROI: I thought you might be lonely. No one sees you except Data.
TAM: Lonely? I can hear everything that everyone on this ship thinks. No one besides you seems to be missing my charming
TROI: You want them to dislike you. Why?
TAM: Because I'm not a nice man. Okay, okay. Because they scare me. They're too many minds. I can't shut them out. I never could learn. All their loves, their hates, their fears, their needs. It's like a tide that never ebbs. I could drown.

When the Enterprise is attacked by Romulans trying to reach Tin Man first, Tam reads the mind of the commander of that ship and knows their full plan, and thus he gets Tin Man to attack the Romulan ship and destroy it (damaging the Enterprise in the process).

Tam represents the only Star Trek telepath that could casually invade minds like this and not at least have people "creep out". Whether this was due to his being born this way or being a valuable Starfleet resource is unclear.


(Thanks to Paul D. Waite for finding the episode I was thinking of)

In the TNG episode The Price there is a human named Devinoni Ral who is negotiating for control of a stable wormhole. Deanna Troi is immediately drawn to him. Eventually he informs her that he is in fact quarter betazoid, the only one of five siblings who inherited empathic abilities. Deanna ends up having issues with his use of these abilities. He hides his heritage and empathic abilities, and Deanna says he does so not because he fears those abilities would make others uncomfortable, but so he can unfairly leverage them in negotiations. She later calls him out over a staged conflict meant to seal the deal for his side in the negotiations (which it did, but it turns out to be a Pyhrric victory for unrelated reasons). She says she was obligated to reveal what he was doing and how.

So they don't spend a lot of time sitting down and hammering about the ethos, but it is made clear that, at least from Troi's standpoint, it is unethical to read minds of people who do not know you have this ability, and unethical to use such mind reading for personal gains and to manipulate a situation.

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