The Australasian colonial legal history library is an AUSTLII project.
It is chiefly legislation and case law.
There is also a section for Law journals and legal scholarship concerning the colonial period. This seems to be based on the most relevant 5% of results of a pre-set search. You get the search summary at the top of the results list - always good to know where your results come from.
Here's a tip: if you can't see where your search results come from, don't trust them. Search results are essentially the answer to a question, so you need to know what the question is in order to understand the answer. I'm really aiming this comment at Westlaw NZ, whose new site does not yet give you an adequate summary of your search strategy. But something similar happens here: within the Law journals and legal scholarship section you can click a link to limit results to New Zealand journals; you get an appropriate reduction of hits (from 382 down to 27), but the search summary does not tell you that it has applied a limit. My inner control freak can't cope with this, so I'm probably better off searching AustLII or NZLII myself and building up my own criteria.