Federal agents and Canadian LE were working a joint investigation. An agent's actions - recording license plates - drew the attention of local LE who were not pleased with being left out of the loop.

"A deputy contacted the man, who identified himself as Richard Kurina, a Canadian police officer with the Lethbridge Police Department working with a Royal Canadian Mounted Police task force. According to the sheriff's office report, Kurina said the task force was designed to catch Canadians smuggling illegal firearms into Canada and that he was with another officer, Agent Craig Howe with the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives."

https://helenair.com/news/state-and-reg ... dium=email

(Sheriff) "Slaughter said he expects next legislative session, which begins in January, to see passage of a bill that would require federal agencies to make contact with local law enforcement before launching an investigation on the ground. Such a law would further validate his stance as a "constitutional sheriff."

Slaughter is a cascade County Sheriff. Gun Show was in Great Falls, MT.

Most encouraging seeing yet another elected sheriff striving to validate "constitutional sheriff".

Wonder if the Canadian agent had a work visa

Also wonder if Great Falls MT falls in the 100 mile border zone. Hard to tell from the maps, it's pretty close

Are you referring to the zone within the US that US Customs can operate in? Pretty sure that doesn't apply to Canadian cops or the ATF.