there's 2 treatys in new zealand, the treaty of waitangi and te tiriti o waitangi. they are supposed to be the same thing but due to poor translation they promise different things. the maori believe they have the rights outlined in the maori version and the government is presenting a bill that will clarify the interpretation of the treatys into law, which will cede sovereignty of the maori.  essentially they will lose all their gibs and be treated like everyone else. hana is a member of te pati maori, the maori party, and started a haka in opposition to the proposal of the bill instead of just voting "nay" because the "aye"s already won, and caused parliament to be suspended.
New Zealand