unforgivable curses

[monika_zaboklicka]

No: HPFGUIDX 130564

OK, my question is: why are unforgivable curses unforgivable?
General subquestion: why they are illegal only when used against 
other humans? What about goblins, centaurs, Veela etc? Don't they 
have any legal protection? 
1. Cruciatus - that's the easiest one; probably invented for torture 
in the first place. I can imagine lawful use of that one - in the 
situations when Muggle doctors would have used electroshocks, but I'm 
sure healers have other methods of shocking their patients.
2. Imperius - that's a spell that might be very easily misused, but 
in my opinion is not evil itself. It can be used to stop an attempted 
suicide, calm down panicking people etc. Quite a number of lifeguards 
would have given their whistles to be able to say "Imperio! Stop 
beating around the water and trying to kill John, he wants to help 
you. Swim to the shore. OK, Finite incantem." 
Furthemore, if wizards are so much against influencing the minds of 
people, why do they use Obliviate on regular basis?
3. Avada Kevadra - the only one that does not seem to be rooted in 
Latin, therefore I suppose it was not invented in Europe. But that's 
beside the point. AK always seemed to me to be an uncomfortable 
curse. It's too long:
"Avada Ke..."
"Crucio!"
"Ke...aaargh!!!"
Six syllables - that's too much for an easy use in a battle. My pet 
theory is that it was, in fact, a curse for executioners, who weren't 
afraid that their victim might curse them back before they finish, 
but would want to make sure that the people they cursed remained dead.

And one more question: can you come back as a ghost if you were 
killed by AK?