Happy Birthday is the sort of congratulations that gets worse with age. For the past 50 years in New Zealand, however, it’s actually gotten better, that is until now. I’m here at the annual Waitangi Day Celebration, where thousands of people have come together to commemorate New Zealand’s birthday, the 1840 signing of the Treaty of Waitangi or Te Tiriti o Waitangi: the agreement between British and native Maori leadership which gave birth to what we now know as New Zealand.

The thing is, Waitangi Day has only really been a day of celebration since the 1970s, when New Zealand’s jurists began to revise their understanding of the agreement, transforming it from a tool used to dispossess Maori people of their rights and lands, into a key document defending those rights.

Yet the mood here this year is a little less jubilant than normal, because the current government wants to reverse these revisions: a move that could be disastrous for the Maori. So, what is it that keeps getting reinterpreted, and why does it matter so much?

Back in the 1830s, the British didn’t technically have any legal presence on these islands, but some British subjects had begun settling here. Unfortunately, lawlessness proved an issue among these settlers, so Maori leaders invited the British to establish some sort of government to keep them in line. In February of 1840, a few representatives arrived to do just that. In only four days, the treaty was drafted in English, translated overnight into Maori, and within just a few days signed by several dozen chiefs, before being copied and sent across the country to be signed by hundreds more.

You may have noticed a potential problem: that translation. See, a few key words in the Maori version don’t translate perfectly to English and leave one crucial question unanswered: whether Te Tiriti preserved Maori “sovereignty” that is self-rule and self-government in their lands or merely “property-ownership” subject to the authority of the British crown.

And that’s a big disagreement, so it shouldn’t come as any surprise that when the British began asserting their sovereignty, the Maori, who didn’t believe they’d ceded anything like that, chafed at their ambition, and went to war over it. How that all happened is way more intriguing than you could even imagine, and you don’t want to miss our 20-plus-minute deep dive into that drama in two weeks. So…subscribe. Anyways, after the wars, the British confiscated territory and abused the agreement’s language to justify massive land purchases at fire sale prices.

At first twisted beyond recognition, the treaty eventually fell out of legal use entirely by the 1900s—when, by force of arms and sheer demographic pressure from the waves of settlers, British sovereignty had been all but totally secured. But the Maori didn’t forget Te Tiriti o Waitangi. As they wrestled with the existential challenge of survival in this new country, this agreement—hastily written and poorly translated as it might have been—remained solid proof of their rights.

But it wasn’t until 1975, after decades of pressure, that the government began taking these demands seriously and established the Waitangi Tribunal whose mission was to look into the history of land seizures and correct violations of the 1840 treaty. Over time, the tribunal’s power grew, and New Zealand courts formally codified the Treaty as binding law. More reforms followed, endowing the Maori with a special sovereign rights and input in key areas of government, like natural resource management.

All of this was based on the notion that the treaty signed by the hundreds of chiefs guaranteed the Maori not merely property rights but sovereignty over their lands and possessions: a hugely consequential reinterpretation that transformed how New Zealand was governed.

Yet, this status quo is far from written in stone. Last October, a new conservative coalition government was elected to run the country, and one small party which made it in the coalition, the ACT party, believes this understanding of Te Tiriti undermines equality before the law. They want to hold a referendum on Maori co-governance and re-re-interpret the principles of Waitangi to reduce or abolish special Maori rights, a potentially tragic reversal of the gains made since the 70s.

Yet ACT’s appeal to the principle of equality before the law, while admirable in concept, is a sort of logical trick. First, because if the rule of law is the core principle of a just society—and it is—surely that includes faithful legal adherence to lawful treaties, such as Te Tiriti o Waitangi, even retroactive enforcement where terms were illegally violated in the past. And second, because to subject Maori to the same law as other Kiwis, pre-empts the very debate which is about whether Maori have some unique sovereignty or are mere subjects of the New Zealand government.

That said, not everything ACT or the other Conservatives want to do would violate the Waitangi Treaty. Today, special rights accorded to Maori include priority access to healthcare ahead of other New Zealand citizens: something that doesn't really have anything to do with what the Treaty of Waitangi was about. For now, it looks like the senior coalition partners might not be with ACT on all of these measures, but only time will tell what happens next.

One thing, though, we know for sure. While every Waitangi Day may come with its share of controversy, and for many Maori it’s a painful reminder of past and present woes, this year it cuts deeper, revealing just how tenuous a foundation Maori rights rest on: a few vital words and little more, which for most of New Zealand’s history, amounted to…nothing.