I'm not sure. Is utilizing the feature that no guard is watching that expensive bracelet in the store illegal?
But in all countries where crypto-currencies are not considered money, is it illegal to double-spend bits?
If I find a funny-looking stone, and promise to give it to you in exchange for goods, it would be fraud to give the funny-looking stone to somebody else instead. Cryptocurrencies are no more "money" than the funny-looking stone, but one could still commit fraud with them.
Stealing a bracelet from a store is made illegal typically through the force of a state.