It had been two days since U.S. lawmakers negotiated all night to finish rules that would reshape the business of Wall Street. The 20-hour session left legislators, aides, lobbyists and regulators exhausted. Almost no one had a grip on all the details.

Then Annette Nazareth stepped in. That Sunday morning, she e-mailed a dozen Securities and Exchange Commission officials about the bill that would become the 2,300-page Dodd-Frank Act.

Nazareth, herself a former SEC commissioner, represents the biggest banks and securities firms as a partner in the Washington office of Davis Polk & Wardwell LLP. She attached an annotated copy of the measure to her June 27, 2010, e-mail, marking changes made during the wee hours. It could be an invaluable tool for an agency hard-pressed to analyze the bill on a tight deadline.