Drivers in Fort Worth, Texas were stopped by police and directed into a parking lot, where they were asked to give samples of their breath, saliva and blood on Friday.
The request for bodily fluids is part of a study by the National Highway Traffic Safety Administration (NHTSA), which is spending $7.9 million to determine how many Americans drive while drunk or under the influence of drugs.
There were signs posted that said participation was "100 percent voluntary," but it didn't feel that way to some drivers who were flagged down by armed police (video below).
"It just doesn't seem right that you can be forced off the road when you're not doing anything wrong," motorist Kim Cope told NBC Dallas-Fort Worth. "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."
"They were asking for cheek swabs," added Cope (pictured above). "They would give $10 cash for that. Also, if you let them take your blood, they would pay you $50 for that."
Cope turned the police down, but they pushed her for a Breathalyzer test, which they refused to pay her for.
"I finally did the Breathalyzer test just because I thought that would be the easiest way to leave," said Cope. "It just doesn't seem right that they should be able to do any of it. If it's voluntary, it's voluntary, and none of it felt voluntary."
Fort Worth police originally claimed there was no police involvement, but then police spokesman Sgt. Kelly Peel said today that off-duty police officers did work with the NHTSA on the survey.
"We are reviewing the actions of all police personnel involved to ensure that FWPD policies and procedures were followed," said Sgt. Peel. "We apologize if any of our drivers and citizens were offended or inconvenienced by the NHTSA National Roadside Survey."
While it may seem shocking, CNN reported earlier this year that the NHTSA has been doing this survey for decades. The last survey was in 2007 and included the blood and saliva samples, without any controversy.
In the 2007 survey, about 7,700 gave saliva, while 3,300 gave blood samples. The final results showed that 12.4 percent had alcohol in their bodies while 16 percent showed marijuana, cocaine or over-the-counter or prescription drugs in their system.