document updated 9 years ago, on Oct 22, 2014
As of July 2014, US citizens will be taxed on their worldwide income, even if they live and work entirely abroad. The affects dual citizens particularly hard.
http://en.wikipedia.org/wiki/Foreign_Account_Tax_Compliance_Act#Controversy
http://www.huffingtonpost.com/wendy-n-powell/expatriate-tax-sense-or-b_b_5716039.html
http://blogs.wsj.com/washwire/2012/05/18/tax-history-why-u-s-pursues-citizens-overseas/
http://www.cbc.ca/news/politics/canadian-banks-to-be-compelled-to-share-clients-info-with-u-s-1.2437975
http://www.cbc.ca/news/canada/u-s-fatca-tax-law-catches-unsuspecting-canadians-in-its-crosshairs-1.2493864
http://world.time.com/2013/01/31/mister-taxman-why-some-americans-working-abroad-are-ditching-their-citizenships/#ixzz2qQrfCb00
http://www.theguardian.com/money/2014/sep/24/americans-chased-by-irs-give-up-citizenship-after-being-forced-out-of-bank-accounts
http://isaacbrocksociety.ca/2014/09/15/democrats-abroad-publishes-fatca-research-fatca-affecting-everyday-americans-every-day/
http://globalnews.ca/news/1072303/over-3100-americans-renounced-citizenship-last-year-fbi/