...First signed in 1840 between the British Crown and more than 500 Maori chiefs, the Treaty of Waitangi lays down how the two parties agreed to govern. The interpretation of clauses in the document still guides legislation and policy today.

Rulings by the courts and a separate Maori tribunal have progressively expanded Maori rights and privileges over the decades. However, some argue this has discriminated against non-Indigenous citizens.

The ACT New Zealand party, a junior partner in the ruling center-right coalition government, last week unveiled a bill to enshrine a narrower interpretation of the Waitangi treaty in law...