The new gun law passed in April after a truncated select committee process. It outlawed most military-style semi-automatic weapons and associated parts.
The Kiwi Party argued that the Treaty protected Māori rights to taonga (treasure), and that included "firearms of a nature" for self-defence and resistance.
But Wylie said it was "alarming" to claim that taonga included anything that could deliver a lethal force such as military-style semi-automatic firearms, and dismissed this as "entirely speculative and without foundation".
He added that this line of argument was not even relevant because the Treaty of Waitangi did not confer enforceable legal rights.
The party also argued that the law violated private property rights and the Bill of Rights 1688, which has a clause about the right to defend yourself with arms.
But Wylie said the clause was about Protestants and included the words "as allowed by law", that the gun law did not ban all firearms, and that the right to private property was never absolute; the Government can take property under, for example, the Public Works Act.
Other aspects of the claim were dismissed because a court could not judge the validity of a law, Wylie said.
"Parliament is supreme, and the courts do not have a power to consider the validity of properly enacted laws."
Gun Control NZ co-founder Philippa Yasbek said the decision "put to rest" a number of arguments put forward by the gun lobby, including the right to bear arms in New Zealand.
She said it was "offensive" to suggest that the Treaty included a right to have military-style semi-automatic firearms.
"I'm not sure the Kiwi Party has a particular interest to Māori rights under the Treaty generally. They're merely trying to throw everything in the hope that something will stick."
Kiwi Party counsel Graeme Minchin disagreed, saying that the Treaty conferred the same rights for Māori as for British citizens, and if Treaty included the right to bear arms for Māori, that right should apply to all New Zealanders.
He said the party had paid $6500 in court costs to the Crown for the High Court case, and would fight its case all the way to the Supreme Court if it had enough money to do so.
The party's main arguments were that the process had lacked appropriate public consultation, that there was a constitutional right to bear arms, and that the gun law was invalid because MMP was not representative of the people, but the "will of the party".
"Parliamentary sovereignty is not absolute. It has to essentially mirror the will of the people."