It's an illusion, this thing called a "right to privacy." This becomes apparent when the feds can do something like this:

Some drivers along a busy Fort Worth street on Friday were stopped at a police roadblock and directed into a parking lot, where they were asked by federal contractors for samples of their breath, saliva and even blood.

It was part of a government research study aimed at determining the number of drunken or drug-impaired drivers.

"It just doesn't seem right that you can be forced off the road when you're not doing anything wrong," said Kim Cope, who said she was on her lunch break when she was forced to pull over at the roadblock on Beach Street in North Fort Worth.

The National Highway Traffic Safety Administration, which is spending $7.9 million on the survey over three years, said participation was "100 percent voluntary" and anonymous.

But Cope said it didn't feel voluntary to her -- despite signs saying it was.

"I gestured to the guy in front that I just wanted to go straight, but he wouldn't let me and forced me into a parking spot," she said.

Once parked, she couldn't believe what she was asked next.

"They were asking for cheek swabs," she said. "They would give $10 for that. Also, if you let them take your blood, they would pay you $50 for that."

At the very least, she said, they wanted to test her breath for alcohol.

She said she felt trapped.

"I finally did the Breathalyzer test just because I thought that would be the easiest way to leave," she said, adding she received no money.

Fort Worth police earlier said they could not immediately find any record of officer involvement but police spokesman Sgt. Kelly Peel said Tuesday that the department's Traffic Division coordinated with the NHTSA on the use of off-duty officers after the agency asked for help with the survey.

"We are reviewing the actions of all police personnel involved to ensure that FWPD policies and procedures were followed," he said. "We apologize if any of our drivers and citizens were offended or inconvenienced by the NHTSA National Roadside Survey."

"Arbeit macht frei" ("Work makes you free") read the sign above the gate to Auschwitz. Much the same way that signs indicating  that participation in a federal study is "voluntary." Who are they kidding? I'll bet that 90% of drivers who were stopped had the exact same reaction as Ms. Cope.

Anyone in the Fort Worth government ask what the hell they needed DNA samples for ("saliva" samples? HA!)? Or blood samples? If it's a study on drunk driving, why a breathalyzer and blood work?

It might be a screw-up by local police. But I don't know too many people - except the homeless and destitute - who would sell their DNA for 10 bucks.

Voluntary my backside.