CERA issued a statement to Stuff last night about its banning a protest from the Red Zone, and dug itself a deeper hole:
"Information subsequently came to Cera's attention that this visit ... was in fact part of a political event ... and media had been invited to be present.
"In light of this information, Cera reconsidered allowing access, and came to the view that access should not be granted for this group.
"Cera is of the view that its staff, being public servants, should not be dedicating time to escorting a group whose purpose is holding a political event. Cera routinely grants access to the rebuild zone for parties who have a reasonable purpose for visiting this area, and provides escorts as required."
Lawblogger Andrew Geddis describes this view as "completely illegal", and the view that political events are not a "reasonable purpose" as being "quite outrageous". I agree - and I expect the courts would do likewise. Like Andrew, I would love to see CERA's BORA advice on this view, but I doubt there is any. From the quote above, its pretty clear that they're just making it up as they go along to suit themselves and their Minister, without any thought for the law. And that is simply unacceptable.
Meanwhile, you can read an account of what happened yesterday from one of the participants here.