The Democratic Party's former point man on financial regulation has a low estimation of Sen. Elizabeth Warren's pet legislation.

Appearing Wednesday before the House Financial Services Committee he used to head, former Rep. Barney Frank, the architect of the 2010 Dodd-Frank financial reform law, dismissed the idea of reinstating Glass-Steagall, the Depression-era law that split investment banks from commercial banks that Warren has advocated reinstating.

Frank, sporting a beard and facing a portrait of himself hanging on the committee room's wall, was asked by Rep. William Lacy Clay, D-Mo., if he favored the bill to effectively recreate Glass-Steagall introduced by Warren with Sens. John McCain, R-Ariz., Maria Cantwell, D-Wash., and Angus King, I-Maine.

Frank responded that the Glass-Steagall separation of banks that take deposits from banks that make speculative investments would not have prevented the financial crisis.

"Glass-Steagall is a 70-year-old bill," Frank said. "I think the things I talked about as having caused the problem – the invention of the financial derivatives without backing, credit default swaps, insurance not regulated in the way that insurance should be regulated, securitization of mortgages — Glass-Steagall wouldn't have stopped any of that,” Frank said. "You could have made all these bad mortgage loans," he added.

Frank explained that he did vote against the 1999 bill that repealed Glass-Steagall — but only because the legislation didn't contain enough of the regulation he thought was necessary, and not because he was against removing the Glass-Steagall prohibitions.

Simply breaking up the big banks isn't a solution, either, Frank argued. He said that too much complexity, not just size, was part of the problem, and that the Volcker Rule, a Dodd-Frank provision intended to prevent banks from placing bets for their own profit with depositors' money, helped reduced complexity.

"The other problem" with breaking up banks, Frank said, "is people say, 'well, the banks are too big.' My question is: What’s the level at which you gotta get them down?"

In a CNN op-ed published last week, Warren and her co-sponsors called the proposed Glass-Steagall regulation a "proactive, structural approach to reducing bank risk" that should be "far preferable to risk-management through over-regulation."

But Frank said Wednesday that the purpose of his law was to prevent the practices that led to banking crises, rather than trying to end the phenomenon of "too-big-to-fail" banks.

"By stopping these irresponsible loans and making people stand behind the financial derivatives, you hope very much to make it unlikely that people will fail," Frank said during the nearly four-hour hearing.

"If there hadn't been bad loans and [the bailed-out insurance company] AIG hadn't sold credit default swaps to people who had bought securities from these bad loans with no idea of how much they owed, we wouldn't have that kind of a problem," Frank argued.