Re: I P v 6. . . i s. . . d i g i t a l l y. . . *s i g n e d*. . . e v i d e n c e
Except that all major OSs now support privacy extensions - I can't remember whether they have to be turned on or are the default. With them, the device will use varying addresses not tied to the MAC address.
But even without that, since the IPv6 address is a) easily manually set, and b) the MAC address can normally be changed anyway, while the IPv6 address does in theory uniquely identify a device - it's not reliable enough to be used as evidence.