Globe and Mail is reporting Group Plans Constitutional Challenge to FATCA.
John Richardson:

“The thing is an unbelievable joke,” said John C. Richardson, a Toronto lawyer who serves as ADCS co-chair. “… I am very confident in our legal position … , no ifs, ands or buts about it. In fact, if [C-31] is not a violation of the Charter, then the Charter doesn’t mean anything at all.”

Finance Canada’s reply were the standard talking points–and no comment about the Charter.
But Kate has something to say;

“I’ve never worked there, I’ve never been to school there, I’ve rarely travelled there,”said Kate, who is supporting ADCS and spoke on condition her last name would not be published. She said she feels betrayed by Canada.
“I would like other Canadians to realize that their rights and freedoms aren’t any safer than my rights and freedoms are. I haven’t done anything wrong. I was just born in the wrong country. And the Canadian government is having no problems just deciding that a foreign country can have my information. So if my rights and freedoms can be thrown under the bus, then all Canadians’ can be. That’s why I think people should be concerned about it.”