Federal regulators have had at least 89 meetings with outside groups, most of them big banking interests, about the controversial "Volcker rule," the provision in the Dodd-Frank financial law that prohibits banks from making bets with their own money. The effort to curb the practice, widely held to be a contributor to the 2008 financial meltdown, was the subject of a hearing in Congress today.

Representatives of the same agencies that met with these outside interests testified that the Volcker rule would be difficult to implement. "One of the more difficult tasks in implementing the statutory prohibitions is distinguishing between ...