LOUISVILLE, Ky. — In July 2005, Vernon L. Jackson returned home to Louisville from Washington, where he had just met with Representative William J. Jefferson, the Louisiana Democrat who had been helping promote his fledgling digital-technology company. David Harper, a lawyer for the company, said he had never seen Mr. Jackson so demoralized. For nearly five years, the inventor and the congressman had carried the message that Mr. Jackson’s company, iGate, could help close the “digital divide” by delivering high-speed Internet access to poor blacks around the world. They had flown to Africa to seek business opportunities, and they had...