On the July 4th U.S. holiday, some Londoners held an anti-American party.

It included flying the American flag upside down.

The group, including about half a dozen who did not want to be identified, were reacting to FATCA, the Foreign Account Tax Compliance Act.

The act requires Canadian banks and the Canada Revenue Agency to identify U.S. taxpayers to the U.S. Internal Revenue Service.

The objective of FATCA is the reporting of foreign financial assets.

Up to a million Canadians that have ties to the U.S. and could end up owing Uncle Sam.

"I think it's safe to say those of us here today don't have much loyalty left to the United States and haven't since this attack came into our lives,” says Lynne Swanson.

All but one in Swanson’s group is American born and each has lived and paid taxes in Canada for 25 to 40 years.

They’ve always been required to pay any amount owing to the U.S., but now with the Harper government agreeing to FATCA, they fear Uncle Sam will have a better chance of finding them  and their bank accounts.

“If this was being done by China, Russia, Iran or Eritrea, there would be outrage," says Swanson.

She is the only member of the group revealing her identity.

Speaking for the others, she says Canadian leaders have let this group, who are all now Canadian citizens, down.

With the federal government agreeing to FATCA, the ex-pats say they'll look at a legal challenge that could cost $1 million or more.

“It's caused depression. It's caused anxiety. It's caused a lot of issues for our family that we have to deal with. And it's all because she's not being protected by the Canadian government,” one man says about his wife, who came to Canada at age five.

Swanson has renounced her American citizenship in the hopes of staying off the U.S. radar.

She expects more Londoners and Canadians with dual citizenship to renounce it, even it if means losing their right to travel and seek work in America.