Introduction 

In New Zealand, as in other English law countries, the notional or skilled addressee plays a centre-stage role in both obviousness and insufficiency challenges to the validity of a patent. There are many terms for what one New Zealand judge colourfully described as “this wraith-like creature who stalks the Reports of Patent Cases”¹. Some of these terms were collected by Finkelstein J in Root Quality Pty Limited v Root Control Technologies Pty Limited², namely the “notional skilled addressee”, “the uninventive skilled worker in the particular field”, “the non-inventive worker in the field”, “the person skilled in the art” and finally “the non-inventive hypothetical skilled addressee”.