For instance, lately I've been reading about the growing popularity of implantable microchips known as Radio Frequency Identification Devices, or RFIDs. Last month, The New York Times ran a trend story about the tiny subset of technogeeks getting "tagged" with RFIDs, enabling them with a wave of the hand to turn on their computers, unlock their cars, commune with their electric toothbrushes, and so on. Now comes a front-page story in The Washington Post about the use of RFIDs as a way for health-care providers to access patients' medical records. Developed to track livestock, each RFID contains a numeric identifier that can be read by a scanner at close range, much like a bar code. Over 6 million of the devices have been implanted in domestic pets, just in case Fido or Fluffy goes missing, and the market for humans seems even more promising. Already, the Mexican government uses the implants to control access to certain offices, and one Ohio-based security firm uses them to limit access to the surveillance videos the company warehouses.

Understandably, privacy advocates are melting down about the possible abuses of such chips, forecasting a dark, dystopian future in which everyone must be tagged in order to obtain such life essentials as a driver's license, bank account, voter registration card or low-fat caramel mochaccino. But it was Marc Rotenberg of the Electronic Privacy Information Center who really got me to thinking about the ominous Big Brother potential of these devices.

"We're just waiting for the first case where a convicted sex offender on condition of release is required to have a VeriChip implanted," Mr. Rotenberg warned the Post.

Since RFIDs are passive identifiers rather than active tracking devices, Mr. Rotenberg apparently envisions a future in which scanners have been installed for private use in enough office buildings, homes, churches, parking garages, restaurants and porn shops to let law enforcement effectively track an individual's every move. But even assuming that the government gets a wild hair and starts installing scanners in schools and rec centers for the express purpose of keeping an eye out for child molesters, what of it? For my money, we'd be better off outfitting most of these guys with something closer in kind to that charming little ankle bracelet Martha Stewart got to wear during her house arrest.

Now before anyone starts freaking out about the slippery slope or about what a gross violation of ex-cons' rights tagging would pose, I want to make two points. One, let's all just admit that, whether wielded by pro-choicers, stem-cell-research opponents or anti-gay-marriage crusaders, the slippery slope argument is kinda lame - the last, desperate refuge of an opposition that can't marshal sufficient stand-alone objections to the specific issue at hand. (Unless we draw a line in the sand now, soon we'll be overrun by an army of lesbian clones demanding to marry their pet Dobermans!) So let's stick to the narrow question of tagging some of the more loathsome varieties of sex offenders.

Fair or not, our current legal system already treats sexual predators differently than other criminals. Anyone convicted of a sex crime can, upon release from prison, look forward to a lifetime of humiliation and restricted freedoms imposed in the name of public safety. Currently, all 50 states have some sort of "Megan's Law" on the books, requiring sex offenders to register their whereabouts with local law enforcement authorities any time they change addresses.

Cities and states across the country are rushing to pass legislation barring sex offenders from living within so many feet of schools, child care centers, parks, playgrounds, bus stops, swimming pools, libraries and any other areas where children congregate. Last year, a group of Texas developers announced plans to create sex-offender-free neighborhoods by requiring all homebuyers to pass a background check and to sign an agreement never to sell to a convicted sex offender. And in 2001, a Texas judge required on-probation sex offenders to post large warning signs in their yards.

Compared to all that, what's a chip in the hand (especially one that wouldn't actively track a perv so much as let police know if he began frequenting, say, P.S. 117 or the boys' restroom at Chuck E. Cheese)?

To clarify, it's not that I'm losing sleep over the emotional pain and suffering of sexual predators, particularly those who target kids. What I do find troubling, however, is the questionable efficacy of some of our preferred perv-tracking tools.

Recently, the Times ran a front-page feature about the unfortunate impact of Iowa's restrictions on where sex offenders may reside. For starters, these no-perv zones are constricting predators' living options to the point that some men have taken to sleeping under bridges or in their vehicles - how's that for enhancing public safety? - while others have congregated in trailer parks and motels just beyond the buffer zone, creating predator hot spots.

More problematically, a growing number of offenders, finding the restrictions too onerous, are choosing to thumb their nose at the system and disappear altogether - presumably without following proper registration protocol at their next port of call. Iowa authorities estimate that three times as many sex offenders are now missing as before the law took effect last fall.

So why shouldn't we work on fine-tuning the technology to keep tabs on a bunch of kiddie molesters? As a nod to the perps' inalienable rights, we could - as Mr. Rotenberg suggested - make tagging a voluntary alternative to longer prison stays. Civil liberties and privacy advocates should, of course, fight for responsible limitations on who could be tagged, where scanners could be placed, and when and by whom someone's files could be accessed. But we shouldn't dismiss the public safety potential of whole areas of technology simply because Rotenberg and Co. fear the approach of the lesbian clones.

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