Toronto law firm Rochon Genova LLP is launching a class action lawsuit against Facebook.
The suit alleges that the social media giant harvested private messages sent by its customers in order to attract ad revenue - a move lawyer Joel Rochon says is deeply disturbing.
The social network stopped harvesting its users emails in 2012, following an expose by the Wall Street Journal.
But Rochon says it never acknowledged its actions or apologized to its users.
He thinks Facebook violated a fundamental trust its 18 million Canadian users placed in it.
"Private messages are sancrosanct, and to find out now that Facebook has been intercepting and scanning those messages for commerical purposes is very disturbing."
Rochon says a dollar figure has not yet been advanced, but says the damages being sought will be substantial.
He adds that he hopes the action will go forward within the next couple of months.