An iwi says the Supreme Court decision on Maori customary rights is perplexing

The court's ruled customary marine titles come down to control and continuity of use in an area - following an Attorney-General appeal.

It's rejected the Court of Appeal's judgment from October last year - calling it a narrow interpretation of criteria.

Ngai Tahu chairman Justin Tipa says the Supreme Court decision significantly raises the bar for proving customary title.

He questions how they're supposed to prove exclusive use and occupation in a strict sense, when in many cases the law itself or crown treaty breaches meant they couldn't exclude others.