Fyi All Walking sticks are not illegal! They are in some places because their droppings actually carry eggs. But in many places certain species of walking stick are native and there are not laws against owning them. The Northern walking stick seems like the most legal one. It's legal in oregon and washington I know atleast. The ones here love to eat your ficcus trees up fast!
Note that some species such as Pink Winged (Sipyloidea sipylus) tend to lose their legs very easily. Also it should be noted that some species such as the Australian or Giant Spiny stick insect (Extatosoma tiaratum), the Jungle Nymph (Heteropteryx dilatata) and particularly the Thorn Legged stick insect (Eurycantha calcarata) can and will pinch (with their thorny limbs) and bite if not used to being handled.
Other species such as the American Walking Stick (Anisomorpha bupestroides) and to a lesser extent Pink Winged (Sipyloidea sipylus) have a defensive chemical spray which in the case of American Walking Stick (Anisomorpha bupestroides) can cause temporary blindness and considerable pain to an adult.