There is a well-worn Washington playbook that the financial industry and Republicans use when they want to kill a proposal meant to protect households from dodgy financial practices: They claim the costs of the proposal exceed its benefits.

On Tuesday that strategy appeared to blow up in their faces when Sen. Elizabeth Warren (D-Mass.) spent seven minutes skewering a former senior regulator at the Federal Reserve who she claimed played a “key role in blowing up the economy.” Warren accused Leonard Chanin, a financial industry lawyer critical of post-crisis rules, of failing to police suspect subprime mortgage lending in the runup to the 2007-2009 financial crisis.

The breathtaking exchange captivated the audience of an otherwise unremarkableSenate banking committee hearing meant to highlight the costs of rules targeting abusive practices, part of a years-long Republican effort to ultimately repeal the 2010 financial reform law known as Dodd-Frank.