The other question regarding the halachos of hypnosis only discusses doing it/having it done to you. I would like to know if someone who is already hypnotized (either intentionally or not) is culpable for damages done while in the hypnotic state. Does this fall under adam muah l'olam or oneis? None of the above?
R' Moshe Feinstein ruled that people are culpable for acts committed under hypnosis if there is reason to believe that the hypnotist wouldn't be beyond suggesting to the person to behave improperly (Igros Moshe, YD 3:44). This is comparable to someone that goes to sleep near fragile items and breaks them in his sleep (Tos. Bava Kamma 4a, s.v. Keivan).
To give the quote from R' Moshe:
אך יש לחוש אם הרופא העושה זה הוא חשוד לעבור על איסורי תורה שמא יאמר לו לעשות דבר איסור ולא יחשב אנוס כיון דהביא עצמו לידי כך
But there is concern if the doctor that does this is suspected of violating Torah prohibitions, lest he suggest to him to do something prohibited, and it will not be considered involuntary since he brought this upon himself.
R' Moshe continues and states that if the doctor is an observant Jew, or if there is some other reason to be confident that the person being hypnotized will not be made to violate halacha, hypnotism is not forbidden. Nonetheless, he writes, it is considered disgraceful to become hypnotized for show, and someone who does so in that context may be pasul l'eidus.