The Transportation Security Administration has a credibility problem. And until they fix it, I can no longer accept their assertion that any security procedure-no matter how intrusive -- is necessary.

The new full-body scans are just the latest in a long string of actions by the TSA that demonstrate that they have little regard for the rights of passengers, and worse, for anything resembling logic.

If the TSA wants my trust, there are some simple steps they can take:

1.       Get an ombudsman, preferably one who has experience prosecuting bad cops. Make one available to anyone who has a complaint. Make the process public. Release the documents the same way the courts do.

2.       Quit the evasions. When someone points out that you are contradicting yourself, as here, then the right thing to do is have someone who is in authority answer that criticism forthrightly and clearly, and perhaps, dare I say it, admit to the error.

3.       If you have evidence the screening procedures stopped someone who planned to hijack a plane, or bomb one, I want his name, the dates and the airport. Thus far no such evidence has been presented.

But let's get to the part about trust. The TSA hasn't got any credibility with me because the agency has demonstrated that at best, they evade legitimate questions. At worst, their spokespeople tell outright lies.

A few examples:

The TSA's web site cites a study from Johns Hopkins saying that the radiation levels from its x-ray scanners are safe. I don't doubt that they are, at least for most people. But when I asked Johns Hopkins about the study, they said it shows is that the devices were compliant with standards for exposure. That's a different question than whether they are safe to use - especially for pregnant women and children.

Then there is the issue of the pat-downs. On the TSA's official blog, Blogger Bob mentions them - but gives no indication of what, exactly, an enhanced pat-down means. We have no idea what kind of training the officers get. The TSA supposedly has a Standard Operating Procedure, designed to maintain a professional staff. But of course the manual is secret.

So there is absolutely no way to know how, or whether, a TSA officer would be disciplined for inappropriate touching during a pat-down. There is no way to know what definitions the TSA is using for such touching. There is no way to find out who to complain to.

The TSA claims that the images the scanners get cannot be stored or transmitted. Yet the requests for proposals, as well as the manufacturers own specifications, detail that such images can be stored and transmitted. The TSA refuses to allow anyone to check their claim that said functionality is disabled.

Confronted with the fact that a group of U.S. Marshals, using a millimeter wave scanning machine from Brijot imaging Systems, saved the images, the TSA's Blogger Bob response was to note that they were from a different agency. That says nothing about what procedures are in place to make sure TSA officers don't do the same thing. Trust us, they say. But if the machines have the ability to store images, then that function can be enabled.

The TSA claims that the scanners are optional, and that the alternative is the enhanced pat-down. But on its own blog there are an increasing number of complaints that such pat-downs are given to passengers, as a method of encouraging people to through the scanners. The problem is that without any oversight, there is no way to check the claim one way or the other. There is no way to see whether the standard operating procedure encourages such behavior. There is no way to check anything.

Now, I am all for protecting people from terrorists. But there isn't any evidence that the screening procedures put in place since 9/11 have done that. Terrorism existed before 9/11. In fact, one could argue that it was a bigger problem in the 1980s.

If the screeners caught a would-be bomber, I'd expect a press release. But all we have is the screeners saying they stopped contraband - which could be almost anything from contact lens solution to a real weapon.

The problem is the flawed assumptions built into security screening.

One is that screening everyone all the time is going to prevent a terrorist attack. It won't. Even if everyone flew naked, that would still not solve the problem of surgically implanted or swallowed bombs.

By the time someone is approaching a plane it is already too late; better intelligence on the part of law enforcement beforehand is much more effective. Umar Farouk Abdulmutallab, the infamous underwear bomber would never have gotten on the plane at all if anyone had listened to his father, who called the CIA before his son ever boarded a plane.

Which gets us to the assumption that the major threat is from passengers. Airliners are maintained, cleaned and refueled  by people who the U.S. has precious little control over at other airports. Baggage handlers have been repeatedly involved in incidents of theft. A baggage handler could just as easily put something into a bag. Yet those people who are in a position to do the most harm aren't screened as closely as the average passenger. If I really wanted to attack a bunch of U.S. airlines, I'd get a job as an airline cleaner and leave a handy bomb in the lavatory garbage can. (It's been done).  

Then on to the most insidious assumption: that terrorism is such a grave threat that planes will fall out of the sky without the screening, and that anything the TSA feels like doing justifies it. Before 9/11, your chances of being in a terrorist attack were one in several million. That hasn't changed in the slightest.

But our collective fear of terrorism has. And it's making us hand over a rather large amount of authority to an agency that has not shown it can be trusted with it.