Show me the law

Thanks to Wikileaks, we now know that a New Zealander - Mark Taylor - is on a US terrorism watchlist. And thanks to John Key, we know that he's in New Zealand and that

he's someone that has quite a number of restrictions on him for very good reasons

This is supposed to make us feel safe. It doesn't. Why? Because Taylor has not yet been charged, let alone convicted, of anything. Which makes any "restrictions" on him exceedingly dubious, possibly unlawful, and certainly an extrajudicial punishment.

New Zealanders are entitled, as of right, to freedom of expression, freedom of assembly, freedom of association, freedom of movement, freedom from unreasonable search and seizure, and freedom from arbitrary arrest or detention. Those freedoms can only be restricted by

such reasonable limits prescribed by law as can be demonstrably justified in a free and democratic society

(Emphasis added)

We need to know what these restrictions are, and what statutory authority enables them. Show me the law which allows this. And if there is none, then those who have purported to impose such unlawful restrictions upon a New Zealand citizen need to be held accountable for it.