Ad industry representatives are expected to clash with lawmakers and consumer advocates at Wednesday's Do Not Track privacy hearing before the Senate commerce committee. Sen. Jay Rockefeller, D-W.Va., a vocal critic of industry self-regulatory efforts, called the hearing and consumer advocates plan to use it to push for new laws regulating the online ad business. John Simpson, privacy director for Consumer Watchdog, says: "We need to see the big stick of legislation. It's the only way to drive anything forward."