From the You Find Ethical Controversies in the Strangest Places Dept., this post from “About the Occult”:
“There are many people (about 0.5%) who use PSI [psychic abilities, to you non-X Files fans] to do evil. Are there laws concerning that? Using ESP AT ALL should be ILLEGAL!!! It is UNETHICAL!!!”
The ethical analysis is certainly sound, even if the assumptions are flawed.
Ethics Alarms 
What if the ESP was involuntary? Like, you couldn’t help but hear someone else’s thoughts (like Mel Gibson in “What Women Want”?
Then you’re ethically obligated to alert the person whose thought you are reading that you can “hear” what they are thinking. ESPECIALLY if you’re Mel Gibson.
What if the person’s afraid of being called crazy? I mean, someone has to be the first person to go out and say, “Yeah, I’m actually psychic.” And chances are good that either nobody will believe him or he’ll be ostracized or forced to give up his power.
But Jeff—he or she WOULD be crazy.
Seriously, the rationalization that “nobody would believe me” is still wrong, even when it is true. At least he or she would have tried. If someone ignores a warning, it’s his own responsibility.
This isn’t much of a debate. First, countless people have claimed to be psychic, so anyone who does so now would be far from the first. Second, the immediate response to the statement should be “OK. Tell me what I’m thinking right now.” Then think about Missouri gooseberries until the person give up, and you can stop worrying about it.
Unless, of course, the person says, “Right now, what you’re thinking is that the person you’re talking with is an idiot.”