Police in Fort Worth, Texas apologized this week after officers forced drivers off the road so federal contractors could test their saliva, blood and breath tested for a study on driving while impaired.

Kim Cope contacted KXAS after she was pulled over because she said it "just doesn't seem right that you can be forced off the road when you're not doing anything wrong."

The National Highway Traffic Safety Administration (NHTSA) has insisted that the study, which was projected to cost $7.9 million over three years, is anonymous and "100 percent voluntary."

But Cope questioned how it could be voluntary if uniformed officers forced her off the road.

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

The contractors also wanted to test her breath for the presence of alcohol, but weren't willing to pay anything for it.

"I finally did the Breathalyzer test just because I thought that would be the easiest way to leave," she explained.

Fort Worth police spokesperson Sgt. Kelly Peel confirmed to KXAS on Tuesday that off-duty officers in the department's Traffic Division had assisted with the NHTSA study.

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

A National Highway Traffic Safety Administration spokesperson told KXAS in an email that the study was being conducted in 30 cities across the country. Contractors from Maryland-based Pacific Institute for Research and Evaluation were in charge of the Fort Worth operation, the station reported.

"You can't just be pulled over randomly or for no reason," Fort Worth attorney and civil liberties expert Frank Colosi explained to KXAS.

Colosi pointed out that the contractors were "essentially lying to you when they say it's completely voluntary" because fine print informs drivers that their breath was being tested by "passive alcohol sensor readings before the consent process has been completed."

Watch this video from KXAS, broadcast Nov. 19, 2013.

["Blood Sampling" on Shutterstock]