A Calgary Police van remains in front of a rental home that a Freemen-on-the-Land follower had claimed as an embassy in Calgary on Saturday, Sept. 28, 2013. Training for frontline officers and better information sharing between police and government agencies can help protect law enforcement officials from potentially aggressive "sovereign citizens," says a newly declassified briefing to Canadian police chiefs. THE CANADIAN PRESS/Bill Graveland

The so-called freeman-on-the-land movement, which appears to be gaining traction in Canada, is getting a closer look from law enforcement.

The freemen, who also style themselves natural persons or sovereign citizens, have evolved from a nuisance into a "growing concern" and a "threat to officer and public safety," in the eyes of senior police officials, The Canadian Press reports.

The news agency obtained a presentation prepared for a 2012 conference of the Canadian Association of Chiefs of Police, which recommended more communication between law enforcement and other agencies, including Canada Border Services Agency, National Defence and Canada Revenue Agency.

Freeman Pamphlet by TheCanadianPress

CP noted the freemen had already caught the attention of the Canadian Security Intelligence Service.

The briefing material was obtained by CP under access-to-information legislation, along with a pamphlet prepared for the police chiefs explaining the freeman ideology.

"This movement is based on a decentralized, libertarian ideology, which is often motivated by personal gain, self-gratification or justification of illegal behaviour," says the pamphlet.

[ Related: ‘Freeman’ movement rejects taxes, laws and debts, but is it a threat? ]

According to a Law Society of B.C. bencher's bulletin, freemen "believe that all statute law is contractual.

"They further believe that law only governs them if they choose or consent to be governed. By implication, they believe that, by not consenting, they can hold themselves independent of government jurisdiction."

In practice, that has meant freemen believe they don't require driver's licences or car insurance, don't have to pay taxes or repay debts. They also don't recognize gun-control laws, which figured in a Nova Scotia case last year involving firearms offences and a threat to kill a police officer, CP noted.

Freemen cloak their activities in pseudo-legal documents filed with archaic or nonsensical terms, which they often get notarized to make them official-looking. They file frivolous lawsuits against public officials and, the chiefs' briefing noted, will send a bill for "services rendered," to police after an encounter with officers.

"These bills indicate that if they are not paid a lien will be placed on the 'offender's' [officer's] property," the presentation says, according to CP.

[ Related: Intelligence sharing key to countering 'sovereign citizen' tactics: police ]

Freemen also squat in vacant homes or open land, says the briefing, which was prepared before news reports about an Alberta pensioner whose Calgary rental property was declared a freeman "embassy." Andreas Pirelli, who also goes by Mario Antonacci, stopped paying rent and changed the locks.

The Montreal man, who is also wanted in his hometown on an assault charge, was arrested last month after a judge ordered him and his supporters to vacate Rebekah Caverhill's duplex.

He'd also placed a $17,000 lien on the home for renovation work he claimed to have done. Caverhill told CBC News that Pirelli left the home in shambles, gutting the kitchen and bathroom and leaving garbage and freeman manifestos behind.

[ Related: ‘Freeman’ at centre of Alberta rental dispute wanted in Quebec for assault ]

Earlier this month, RCMP arrested a self-styled freeman who'd taken over a trapper's cabin and trap line in northern Alberta, according to CBC News.

The police chiefs' briefing also recommended officers and judicial officials receive training on the freeman phenomenon.

The B.C. Law Society article, written as a warning to lawyers and notaries on how to deal with freemen, said it's estimated the movement has up to 30,000 Canadian adherents, with U.S. supporters numbering in the hundreds of thousands.

The movement has been on U.S. law-enforcement radar for some time because of its connections to right-wing militia groups.

A 2011 FBI law enforcement bulletin said sovereign-citizen extremists have killed six police officers since 2000, including two Arkansas officers gunned down with an AK-47 during a highway traffic stop in 2010.

[ Related: Freemen movement prompts CSIS, Alberta meeting ]

Its American adherents have included Terry Nichols, who helped plan the 1995 bombing of an Oklahoma City federal building that killed 168 people and injured 680 more, the FBI document says. Its growth has been fuelled by the Internet, bad economic times and seminars that spread its ideology and methods.

"Although the sovereign-citizen movement does not always rise to violence, its members’ illegal activities and past violent—including fatal—incidents against law enforcement make it a group that should be approached with knowledge and caution," the bulletin concludes.