On December 15, Bill of Rights Day, the uproar over body scanners had brought the Fourth Amendment to the front of the public debate. There are legitimate reasons to be upset over invasive, costly and arguably ineffective measures adopted in the guise of protecting national security. But the call to arms over body scanners is a distraction.

First, it's debatable whether body scanners violate the Fourth Amendment. There is a plausible argument that such security measures are reasonable in light of potential hijacking threats. With 9/11 still etched in our national psyche, it's hard to imagine that courts would deem body scanners unconstitutional.

Second and more important, the uproar over body scanners distracts us from far more egregious constitutional violations routinely committed by our government.

The Fourth Amendment explicitly prohibits authorities from conducting "unreasonable searches and seizures" and requires judicially authorized warrants based on "probable cause" that "particularly describ[es] the place to be searched and the persons or things to be seized." Thanks to the Fourth Amendment, police must reasonably suspect criminal activity before conducting a stop and, absent rare exceptions, must secure a warrant, signed by a judge, before conducting a search.

However, in the wake of 9/11, federal agencies have fully ignored these constitutional restraints.

Let's take, for example, the rampant use of national security letters (NSLs) by the FBI. NSLs are requests for information targeting an individual, but issued to third parties, such as Internet service providers, financial institutions or libraries. The Fourth Amendment requires that such information be obtained through a search warrant signed by a judge, supported by probable cause and specifically describing both the target of the warrant and reason for it.

However, the FBI employs NSLs unrestrained by any of these constitutional requirements. In other words, the FBI can access your highly personal and private information on a whim. And it has not used this power sparingly.

The FBI has issued hundreds of thousands of NSLs, with tens of thousands more issued every year. And the Obama administration has pushed to expand the scope of NSLs to include (among other data) your web browser's search history and your friend requests on Facebook.

Just as troubling is the practice of federal agents and government-paid informants infiltrating activist and religious groups. This is nothing new, of course. The FBI's illegal infiltration efforts during the COINTELPRO era have been well documented in thousands of pages of Congressional testimony.

Unsurprisingly, the most recent victim of these efforts has been the Muslim community. The Washington Post recently reported that the FBI recruited, trained and paid a convicted forger to infiltrate a mosque in southern California to gather intelligence. Ironically, worshipers were so alarmed by the informant's talk of violent jihad that they sought a restraining order.

Not only did insufficient evidence eventually force the government to drop the only case arising from that covert operation, but the ordeal damaged the fragile relationship between and the FBI and the Muslim community, undermining one of the most effective tools at our government's disposal for gathering reliable information. This story underscores how clandestine investigations based on profiling are ineffective and counterproductive to our national security interests.

But such infiltrations are illegal in the first place. The Fourth Amendment's requirement of particularized and individualized suspicion renders unconstitutional the despicable practice of profiling suspects based on race and religion - but the FBI does so routinely. Sending informants and government agents on witch hunts to infiltrate religious and activist groups is not just an enormous waste of tax dollars; it's also profoundly un-American.

So, next you consider airport security, remember that the government is merely examining an outline of your naked body. Now recall that, at any given moment and without articulating any particular reason, it can secretly monitor your Internet usage, access your bank transactions, scrutinize your medical visits and prescriptions and intercept your phone calls and emails - and it might even be paying that new guy in your bowling league to gather information on you.

Makes the whole body scanner thing seem pretty trivial, doesn't it?

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