“The Fed’s new restrictions come from the Dodd-Frank Act of 2010, which brought in a wave of reforms after the financial crisis. Under the new rule, banks that are going bankrupt — or appear to be going bankrupt — can no longer receive emergency funds from the Fed under any circumstances. However, it’s important to note that the new rule allows the Fed to judge by its own measures whether a firm qualifies for its emergency aid. The idea is the Fed can still lend to banks during times of emergency, but the bank must be able to pay it back. Yet the true health of a bank in turmoil can be very difficult to assess.”
http://money.cnn.com/2015/11/30/news/economy/fed-adopts-rule-to-end-too-big-to-fail/