Dysfunctions, related to soul and soul-related spells (Trap the Soul, Soul Bind, Soul Shackles, Imprison Soul, Ensul's Soultheft and, maybe, several more):
1. Nowhere in the spell's descriptions was mentioned necessity for target to actually have soul in the first place (And, if you think everyone have souls, just one counter-example: Death Giants)
2. Also, descriptions don't specify how many times target can be affected (So, you can potentially harvest unlimited amount of souls from the very same target and use them to bargain with fiends, or as described in BoVD optional rule "Souls as power")
3. Description of Soul Shackles says:
If the subject is hostile, or if the answer to the question was an important secret to it in life, the subject gains a Will saving throw. A successful saving throw indicates that the spell ends and the soul departs to the afterlife.
Yet it have
Duration: Instantaneous