CBC News has learned the charge against Bert Easterbrook was filed last month under the Statistics Act.
Statistics Canada alleges Easterbrook failed to do his civic duty in filling out the 2011 census in the weeks following the riot.
Michael Vonn with the B.C. Civil Liberties Association says the charge is rare, especially because most Canadians are under the impression the census is no longer mandatory.
"That might be what takes us so off guard around these sort of retrograde charges,” she said.
The Statistics Act still makes refusing or neglecting to fill in the census an offence punishable by a $500 fine and up to three months in prison.
Vonn says the association recognizes the need to collect data but questions the threat of jail time.
Easterbrook told CBC News he “finds it sickening that a tax-paying citizen has to choose between a three-month prison sentence and willingly giving personal, private information."
Easterbrook was caught on camera on June 15, 2011 protecting a truck as rioters tried to burn it and then turned on him in the hours after the Canucks lost the Stanley Cup final to the Boston Bruins.
He was one of several dozen people honoured by the Vancouver Police Department earlier this year for taking action during the riot.
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