Would liberal use of Dominate Person or Geas for the purposes of interrogation count as torture?
I can only answer how my campaign works.
In general, mind control spells in my campaign world are treated legally as equivalent in distaste to rape (one violates the body, the other the mind). So if anything, most people would find them more distasteful than physical torture, and would certainly consider them equally violent. (We don't consider violation of the body less violent if it was done by drugging someone insensible to the act.) Societies that respected individual liberty would probably be more tolerant of torture than the use of mind controlling magic, and more collectivist societies that employed them would strongly tend toward evil. I can imagine a non-evil society or character employing them in a 'Dirty Harry' type situation in an attempt to save a life, but it would likely be in a situation where the character would be, "The life of someone else is more important than my honor", and with the expectation by the PC that they'd suffer for violating social norms even with good motives.
Use of mind effecting spells to cause pain and suffering would be considered to aggravate the crime, and would be considered torture additionally. Whether they found torture evil or just distasteful (or held it in high esteem) would depend on the culture.
Most persons from my campaign world would be appalled by stories where nominal heroes used 'Jedi Mind Tricks' or mind control or probes in a casual manner. Many would find it unforgivable and even those that didn't would only find it justifiable if used in self-defense. There would be nigh universal agreement among 'the good' that Obi Wan's "You don't want to use death sticks" or Qui-Gon Jinn's attempt to Jedi Mind trick a merchant into giving him a deal would be beyond the pale, and death sentence worthy abuse of their abilities.
Beyond that, character's capable of something like 'Dominate Person' or 'Geas' are so extraordinarily rare in my game world, that no judicial system would ever evolve to treat such tools as the norm. Only the most powerful groups or individuals could employ such tools in the first place, and they'd probably want to keep it quiet for a variety of reasons. There are entire nations where no one can employ either 'Dominate Person' or 'Geas'.
Additionally, in most societies (except a few theocracies and hard autocracies) testimony which is gained solely through any sort of magic is inadmissible as evidence. The reason is pretty obvious, as there is no way to collaborate the testimony. If the person can be compelled to talk, then they can be compelled to lie. If a wizard claims that his spell detects or prevents lies, then the testimony is only as trustworthy as the wizard. This would put the judge or jury in a situation where they would be utterly subordinate to the judgment of that spellcaster. Likewise, spells aren't foolproof. Whatever one magic can assert, another sort of magic can deceive. So really, only in societies where a particular temple is explicitly trusted to render judgment that you see even divinations used as anything but an investigative technique. A society might use 'Speak with the Dead' together clues, but with a few exceptions they'd never pass judgment based solely on the testimony of a dead guy or a spirit or a spellcaster, unless they were also the sort of society that made testimony gained through torture admissible.
