Ohio Republican Rep. Jim Jordan, chairman of the Oversight Subcommittee on Economic Growth, Job Creation, and Regulatory Affairs, is demanding answers on a federal study on drunk and drugged driving, saying the methods used to collect the data might violate drivers’ constitutional rights.

The National Roadside Survey of Alcohol and Drugged Driving stops drivers to get samples of their breath, saliva and blood to test for the presence of alcohol, drugs or any combination of the two.

The survey is supposed to be voluntary, but the tests are being conducted by police officers in uniform, causing some motorists to complain that they do not feel they have any choice in the matter. Moreover, the Associated Press reported, the surveyors use something called a “passive alcohol sensor” that tests drivers’ breath for alcohol content before they formally consent to the survey.

“I am concerned that the manner in which the survey is being conducted may infringe upon the Constitutional rights of motorists,” Jordan writes in a letter to Bernard Murphy, the president and chief executive officer of the Pacific Institute for Research and Evaluation, which has been contracted to perform the study for the National Highway Traffic Safety Administration.

“I am concerned about the perceived level of ‘voluntary participation’ in PIRE’s current roadside survey,” Jordan writes. He points out that several police departments have promised not to allow the study to occur in their cities after learning how the survey was conducted.

Jordan requested PIRE provide all documents relating to the dates of the surveys, the volunteers for the surveys, and the police officers used to conduct the survey. He also asks the company to turn over anything related to “any arrests that have taken place in conjunction with the survey.”

In November, the NBC affiliate in Dallas and Fort Worth, Texas reported that motorists felt they had been railroaded into taking the tests.

“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,” Kim Cope told NBCDFW in November 2013, who said she “finally did the Breathalyzer test just because I thought that would be the easiest way to leave.”

According to a NHTSA document from January 2007 called “Pilot Test of New Roadside Survey Methodology for Impaired Driving,” conducted by PIRE, motorists were selected randomly by off-duty police officers, who would signal them into the parking lot where data collectors were stationed. “Few drivers refused to enter the site,” according to the document.

“As the motorist came to a safe stop in the bay,” and before the drivers had consented to participate or been told what they were being asked to participate in, “the data collector recorded basic demographics based on observation (e.g., the number of passengers, use of a safety belt by the driver, and the gender and ethnicity of the driver)” … so that we would have descriptive information of potential subjects who refused.”

Participants were told the survey was “anonymous, voluntary, and can be ended at any time.”

They were then asked a series of survey questions about their driving habits. If they “objected” to answering the questions, they were still “asked … to provide a breath sample before the exited the survey bay.” While they were conducting the verbal survey, a passive alcohol sensor was used on each subject. Participants were offered $10 for an “oral fluid” sample, $50 for a blood sample, and an extra $5 if they agreed to fill out a questionnaire about alcohol use.

Drivers who were found to be impaired in some way were offered rides home by the date collectors, or help arranging a ride home from friends or family.

Jordan asked PIRE to provide the requested data by 5 p.m. on March 25.

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