By adding significantly to benefits for unemployed people without commensurate additions to the incomes of workers, the 2009 American Reinvestment and Recovery Act (a.k.a., "stimulus law") changed 100 percent taxation from a rare circumstance to one that presented itself to about five million household heads and spouses. If Congress had heeded the advice of those calling for a "bigger stimulus," as many as 13 million people would have made more unemployed than they would as workers. Watch this 19 min video to see how such high implicit tax rates became reality.
Viewers interested in more information on this topic: please look at http://www.nber.org/papers/w18591
It happens in Japan too (ht Austen Bannan).