Prominent anti-TPP protestor Professor Jane Kelsey said such monitoring of critics to the controversial agreement was "entirely predictable" behaviour from the Government, and shows the "disrespect the Government has had throughout to people's right to voice their dissent about this negotiation and this agreement".
"This is perfectly consistent with their attempts to shut down democratic engagement with, almost anything, but certainly with the TPPA."
The Government was attempting to make a law and order issue out of the opposition to the agreement, she said, by painting those in opposition to it as radicals who posed a national security risk.
"One of the problems they've had is that the opposition has been a groundswell throughout the country of ordinary people from ordinary communities. If you look at the people who've been engaged in the marches it's been grandmas and grandpas and people with pushchairs," the University of Auckland law professor said.
"That's an image the Prime Minister I'm sure is quite desperate to dislodge.
"We've been seeing them progressively rolling out this strategy, or this attempt to redefine and create a law and order issue out of it.
"If the Government could "whip up some law and order frenzy" in advance of the signing, she said, it believed it could "claw back some support ... for what is largely an unpopular deal".
"The decision to hold the signing in the SkyCity Casino was the first indication that that would be their strategy, they could have decided to have it in a place that was going to be less provocative," she said.
"In addition we have the story then about police holding riot training around the country, and that was clearly set out there to reinforce that message, and I think this latest one is a further indication that they're trying to do a beat up."
She wouldn't be surprised if Mr Key announced that for security concerns the signing would be moved to a more secure venue, she said.
"I just view this as an on-going political strategy to try to redefine the issue from being one of ethics and justice, and democracy and sovereignty to a law and order issue."
Professor Kelsey said she had not herself had a visit from police - she's currently on a speaking tour throughout the country , and had just arrived in Christchurch before speaking to the Herald.
"If they've been to see me I don't know, but I would doubt that they would. I think that they would know that that would just make news."
She did not know of anyone who had been visited by police either, she said.
Civil liberties lawyer Michael Bott said the police action would have a "chilling" effect on freedom of expression and the right to protest.
"These people haven't committed any crime and yet the police are going to conduct a search or an interview, and there are legal concerns with that."
Labour Party police spokesman Stuart Nash says he thinks the door-knocking is "not the way we do things in this country".
"My initial reaction is that it is a little heavy-handed. The protesters have a legal right to protest within the bounds of the law.
"During every single TPP rally, I can't recall any instances where protesters have been violent or aggressive.
"Unless the police know something we don't, the protesters have the absolute right to voice their concerns, as we live in a democracy."
Mr Nash said he didn't blame frontline police for the tactic.
"They're just following a directive from above, and it would be good to know why the police hierarchy feel this is a necessary step, and it would be good to know if they actually know if the protesters plan to engage in civil disobedience."
Police said the visit was part of a national directive to visit activists in the lead up to Friday's protests.
There have been scattered reports of anti-TPP activists in Auckland being called or otherwise tracked down by the police for questioning about their protest plans.
The police's interest in anti-TPP activists comes as opposition to the deal ramps up ahead of the signing in Auckland on February 4.
The Dunedin-based TPP action group - of which Scout is not a member - has planned a talk on the TPP tomorrow, and an "action event" is planned to take place in the Octagon from 12pm on Saturday.
