[Chaos]

Probably the right place.

Beyond the cap on Copy Spells coming within the future, it should be braindead that Copy Spells should be automatically lost if Spellthief is unequipped.



As for legality, Dev's answer on the Lore Thread will determine that, I suppose. However, until then, here's my take:

I imagine that 'Spellthief' would be a rightly feared and likely illegal occupation-- Even if the art of spell-snatching does not permanently damage a mage's arsenal, a Spellthief is still gaining incredible and versatile power from another's hands. Even if the law were to turn a blind eye on them, those who fear their capabilities are likely to get their hands (and wallets) dirty in the name of dealing with these arcane snatchers.

....Of course, since a Spellthief usually involves themselves with illusions, it's quite possible to snatch spells without anyone being the wiser. On the other hand, those who delve into earthen magic are never easy pickings, and one can never be too sure about how effective the smoke and mirrors are, so to speak.