Flickr image courtesy Obama for America

After a fevered, weeks-long debate in the United States over whether X-ray body scanners intrude on the privacy of Americans, it may be that they’re not reliable in the first place at detecting explosives.

Two physics professors at the University of California-San Francisco argued recently that irregularly shaped explosives with uneven edges could slip by unnoticed if a scanner operator couldn’t distinguish them from normal body parts. Wrote Leon Kaufman and Joseph Carlson in a peer-reviewed article for the Journal of Transportation Security:

Even if exposure were to be increased significantly, normal anatomy would make a dangerous amount of plastic explosive with tapered edges difficult if not impossible to detect.

Congressional investigators found earlier this year that there were no assurances a body scanner would have exposed the so-called underwear bomber from last Christmas.

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The Department of Homeland Security is using X-ray technology for more than just looking beneath the clothing of travelers in search of dangerous devices. In September we wrote about a company called American Science & Engineering that manufacturers van-mounted X-ray devices capable of revealing the contents of passing vehicles.

The common use of them by law enforcement could raise constitutional questions since police generally can’t search your vehicle without a reason. But that hasn’t stopped homeland security officials from spending at least $33 million on vehicle scanners in recent years. Customs and Border Protection announced earlier this month that it had inked a new $67 million deal with AS&E for as many as 27 “portals” the agency will use to scan for weapons and other contraband as drivers pass through them. The systems will apparently be deployed at border-entry points.

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Lawmakers in Tennessee will consider a bill next year similar to the one already passed by Arizona that directs local police to determine the immigration status of people they come into contact with and suspect of being in the country illegally.

The Tennessean newspaper finds that private jailer Corrections Corporations of America based in Nashville has given campaign contributions to backers of the law. It’s also involved in a group pushing for the law’s passage. Why might that be the case? Detention contracts with Immigration and Customs Enforcement have boosted CCA’s revenue in recent years.

National Public Radio concluded in an October investigative report that the private-prison industry was involved in a “quiet, behind-the-scenes effort to help draft and pass Arizona Bill 1070.”

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Data mining is a controversial concept in which intelligence and law enforcement agencies sift through oceans of seemingly disparate data and search for evidence of terrorist attack planning or criminal activity. That data can involve personal information like purchasing records, social security numbers and birth dates belonging to innocent people. The Privacy Act of 1974 and other laws restrict how such data can be used.

One way for authorities to make data mining less controversial is to call it something else, or very narrowly define it. Government agencies are required to disclose data-mining activities to Congress each year, but certain of those programs fall outside the strict definition of data mining, like “link analysis,” which begins with a known subject or person of interest. As a result, the nonprofit Constitution Project wants the official definition of data mining to be expanded. According to a report from the group:

With insufficient controls, innocent people could be mistakenly added to terrorist ‘watch lists’ and potentially barred from air travel. Government employees can abuse database access and look for information on the famous or infamous. Careless contractors can lose laptops with unencrypted personal data. These harms can be contained, but only with firm rules that ensure government actors undertake data mining with adequate safeguards and minimize the potential for mistake, misuse and abuse.

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A local police intelligence fusion center in Atlantic, Iowa, misspent $67,000 worth taxpayer money, some of which was used for flowers and “Christmas meat,” according to an audit released Dec. 8. Dozens of such centers were constructed after Sept. 11 so federal, state and local authorities could swap tips about terrorism and crime.

Civil libertarians worry that they’re stockpiling too much sensitive personal data, and it’s not clear fusion centers are contributing meaningfully to the war on terror. Washington has spent at least $426 million developing the centers since 2004.

G.W. Schulz is a reporter for Reveal, covering security, privacy, technology and criminal justice. Since joining The Center for Investigative Reporting in 2008, he's reported stories for NPR, KQED, Wired.com, The Dallas Morning News, the Chicago Tribune, the San Francisco Chronicle, Mother Jones and more. Prior to that, he wrote for the San Francisco Bay Guardian and was an early contributor to The Chauncey Bailey Project, which won a Tom Renner Award from Investigative Reporters and Editors in 2008. Schulz also has won awards from the California Newspaper Publishers Association and the Society of Professional Journalists’ Northern California Chapter. He graduated from the University of Kansas and is based in Austin, Texas.