Great cries of shock and disillusionment are echoing across many precincts of President Obama's political base, particularly among academics, civil libertarians, nonprofit activists and media celebrities. The howls of distress stem from the chief executive's stunning reversal on the scope and constitutionality of domestic surveillance programs at the National Security Agency and elsewhere in the federal government. Although he vociferously opposed these programs while campaigning for president in 2008 and before, Obama began singing quite a different tune once he began working in the Oval Office.

Since then, it has become increasingly difficult to see any light between Obama's position on surveillance programs and that of President George W. Bush, who inaugurated most of them in the wake of the 9/11 terrorist attacks in New York and Washington. What was in 2009 a mostly unspoken discomfort is today becoming a yawning gulf as Americans learn more about the extent to which their daily comings and goings are being captured digitally. Obama's impatient rejoinder that "you can't have 100 percent security and 100 percent privacy" was particularly shocking to his former admirers.

But where were these admirers when Obama's 2012 re-election effort mounted the most powerful presidential campaign ever based on the same basic technology underlying the NSA surveillance -- the capture and analysis of metadata? The heart of NSA's defense of its surveillance -- also of Obama's -- is that the government is only tracking data about telephone calls, not listening to the people talking. Merging billions of bytes of call-data enables officials to identify potentially revealing trends and relationships such as Citizen A calls Citizen B every two days. Since Citizen B has known terrorist associations, Citizen A may as well.

That's how the Obama campaign worked, first by gathering billions of bytes of data about individual Americans on what they buy, where they eat, their hobbies, their political party registration and a thousand other characteristics. Next, the campaign techies harvested individuals who subscribe to certain publications, visit particular websites and donate to selected nonprofits in patterns known to match those of confirmed Obama voters. The NSA uses the metadata to identify potential terrorists sympathizers, much as the Obama campaign used it to locate potential political supporters. It's not coincidental that Silicon Valley denizens were prominent architects of the government surveillance programs and the president's re-election digital strategy.

The problem here is not national security versus individual privacy. It's much more akin to why the founders adopted the Fourth Amendment's guarantee against illegal search and seizure: During the Revolutionary War, the British Army used general warrants to search and ransack private homes and confiscate private property at will. General warrants were purposely vague in order to give the Redcoats maximum leverage. That's why two centuries hence, search warrants must be approved by a judge for specific objects thought to be in a particular location and related to an actual crime.

Note that just as such parameters limit a search warrant's utility, the utility of a database for metadata purposes is its constant expansion. Thus, a government -- or political candidate -- that relies on metadata-driven analyses will inevitably develop an insatiable appetite for knowing more about all Americans, not just those linked to terrorism. In other words, sooner or later, "metadata" becomes the digital way of saying "general warrant."