Senators Sherrod Brown (D-OH) and David Vitter (R-LA) have introduced legislation that would lay the groundwork for breaking up the biggest banks — a cause Sen. Elizabeth Warren (D-MA) has been fighting for since she took office.

To understand why this legislation is so important even though Congress already passed into law a financial reform bill, recall that the biggest so-called “too big to fail” banks on Wall Street are now actually bigger than they were during the financial crisis where they were bailed out.

Neil Barofsky, a New York University academic who served as the watchdog for the Trouble Asset Relief Program (the bank bailout), appeared on CNN last fall and explained how the banks are bigger than ever and that they continue to believe they’ll be bailed out if they fail:

BAROFSKY: If you just look at the map, the fact is the banks are 20 to 25 percent bigger than they were before the crisis. And that we haven’t changed the incentives. The way the incentives are “too big to fail” because of the presumption of bailout is it drives these institutions into taking more and more bigger and bigger risks. Again, the presumptions are they’ll keep the profits, and the taxpayers will eat the losses.

Watch it: