Today's Senate Commerce Committee hearing on the status of Do Not Track development was among the most heated of any recent privacy-related hearing in memory.

Senator Jay Rockefeller, Commerce Committee Chairman, had few kind words for the digital ad industry or digital data collectors during the hearing. Industry is "dragging its feet" on development of Do Not Track, said the Democrat from West Virginia, "and I believe they are doing it purposely."

Launching into a tirade against the ad industry's rhetoric on DNT regarding its potentially negative impact on ad targeting, digital publishers, and the Internet ecosystem, Mr. Rockefeller was adamant that he wanted "to get to the bottom of this controversy," referencing the stalled efforts of the World Wide Web Consortium's work towards developing a DNT standard.

He also stressed the Digital Advertising Alliance's Ad Choices program does not satisfy the mission put forth by the Federal Trade Commission's call for a DNT standard.

Mr. Rockefeller, a Democrat, re-submitted his Do-Not-Track Online Act (originally proposed in 2011) in February. The bill calls on the Federal Trade Commission to oversee development of a DNT mechanism, and was co-sponsored by Connecticut Democratic Senator Richard Blumenthal.

When Mozilla unveiled plans in February to include a default setting that disables third-party cookies in the lateset version of its Firefox browser, the Interactive Advertising Bureau - a key member of the DAA -- promised to fight it. During the hearing, deemed "A Status Update on the Development of Voluntary Do-Not-Track Standards," Harvey Anderson, Mozilla SVP of business and legal affairs and general counsel told Senators industry has not moved forward quickly enough.

"The efficacy of the Ad Choices program remains questionable," he said.

Chasms between what industry says its Ad Choices privacy program does, and what privacy advocates and other observers say it does were exposed by comments from DAA Managing Director Luigi Mastria and those of Justin Brookman, director of the project on consumer privacy at the Center for Democracy and Technology.

In particular, the DAA claims its system always stops data collection when a user opts-out; however according to multiple sources, in some cases opting-out through the program only blocks behavioral ad targeting rather than actually stopping behavioral data collection, as reaffirmed by Mr. Brookman during the hearing.

Mr. Rockefeller acknowledged this, noting, "Companies continue to collect vast amounts of consumer information and only promise not to use this information for specific purposes such as [advertising.]"

He also referred to the World Wide Web Consortium (W3C), whose Tracking Protection Group has been slogging through discussions on developing a standard for browser-based DNT for at least two years.

"The WC3, W3C, whatever it is...has not authority whatsoever," said Mr. Rockefeller. Despite the fact that the organization does not have enforcement or regulatory authority over U.S. companies, both the White House and more recently the FTC have said the W3C is an appropriate forum for self-regulatory development of DNT.

In a speech earlier this month that liberally alluded to Shakespeare, newly-minted FTC Chairman Edith Ramirez suggested, "consumers still await an effective and functioning Do Not Track system, which is now long overdue." She implied the W3C remains a good forum for that initiative. "I therefore urge all players in the online advertising ecosystem to dive into the W3C process with good faith and a resolution to hammer out their differences to develop a transparent Internet advertising system that meets the needs of consumers and advertisers alike."

In its Privacy Bill of Rights, the U.S. Commerce Department also called for a DNT standard to be developed through the W3C.

The W3C's own Peter Swire, co-chair of the DNT development group, suggested detante could come to the increasingly contentious DNT cold war between privacy advocates and the digital ad industry. In a Wired opinion piece published today, Mr. Swire, professor of law at the Moritz College of Law of the Ohio State University, wrote, "A negotiated Do Not Track standard offers the best way to avoid the arms race: It would allow individual users to indicate whether they wish to have personalized ads based on their surfing habits.

It would allow websites and advertising networks to continue their existing cookie-based models with the consumers who don't opt out. And it would help avoid the sizzling controversy and escalation around cookie blocking and technical counter-measures. Most importantly, it avoids the alternative: that the federal government imposes its own solution."