[scan technology] voluntary for now

Like iris scans and ID technology, passengers are given the option of fast-tracking using the new technology or slow-tracking - and many opt for the former:

The "millimetre wave" technology system being tested at Schiphol Airport as part of anti-terrorism efforts is under consideration for deployment in the United States by the Department of Homeland Security.

It differs from the "backscatter" system being tested at some airports, including Phoenix, in that it uses low-energy radio waves, rather than high-energy X-rays, to create a dim outline of a passenger's body.

It's a measure of the way it's currently being used that the Civil Liberties Union is making relatively few waves over it. The question, it seems to me, is for how long it will be voluntary.

Still, one can always stay home, as I do.