READING, Pa. (AP) -- Orange cones and flashing police lights confronted Ricardo Nieves as he rounded a bend on the way to his mother's house. Before he knew what was going on, Nieves said, a man working for a government contractor stepped in front of his car and forced him to turn into a parking lot. There, a woman repeatedly tried to question him about his driving habits and asked for a mouth swab that would detect the presence of illegal or prescription drugs in his system.
Nieves refused. Then he sued, contending his rights were violated.
His Dec. 13 experience has been repeated thousands of times in cities around the country as the federal government tries to figure out how many of the nation's motorists are driving while drunk or high.
U.S. transportation officials call the National Roadside Survey of Alcohol and Drugged Driving, which has been conducted five times since 1973, a vital tool for monitoring the safety of America's roadways. But some motorists and civil liberties advocates contend the government's methods are intrusive and even unconstitutional. Some police departments have refused to partner on the survey or regretted their decision to do so in the wake of public outcry. In Tennessee, legislation that would ban law enforcement from helping out on the survey unanimously cleared the state Senate last month.
In the southeastern Pennsylvania city of Reading, Nieves is angered over what he views as an abuse of power.
"I didn't even have a choice to make a decision" to stop for the survey or keep going, he said. "That choice was taken away the moment he stepped into my right of way."
Conducted in 60 cities around the nation, the survey yields the government's best estimate of the prevalence of impaired driving. It works like this: Motorists are randomly selected -- either by a uniformed police officer or a private contractor working for the National Highway Traffic Safety Administration -- and waved into a parking lot, where they are questioned about their drinking and driving habits, asked to take a breath test, and offered money if they provide saliva and blood samples or agree to answer a more extensive written survey.
Federal officials stress the survey is both voluntary -- a large sign at each survey site says so -- and anonymous, with local police enlisted to provide security and divert selected motorists from the flow of traffic. Any driver found to be impaired is offered a ride home or put up in a hotel.
The survey's supporters include Mothers Against Drunk Driving and the Insurance Institute for Highway Safety, a group funded by auto insurers whose president, Adrian Lund, said it lets researchers and policymakers monitor how national alcohol policies are working. Though the rate of drunken driving has plummeted over the past 40 years, impaired motorists kill thousands a year. Highway deaths involving drunken drivers rose 4.6 percent from 2011 to 2012, when it numbered 10,322, according to federal statistics.
"This is a very minimal intrusion on privacy," Lund said. "If you know that by participating in this survey, (it) means that we may develop policies that make it less likely you're killed by an alcohol-impaired driver, I think that's well worth the price."
But the government's own documents acknowledge concerns about the National Roadside Survey at least as far back as 2007. The tactics used by the Maryland-based contractor, the Pacific Institute for Research and Evaluation, are "not routine by any means," according to a survey methodology that describes how some police departments had balked at participating in the 2007 version of the survey because they believed they were barred by law.
"The major barrier ... was obtaining police department support for the study. In some localities, city attorneys or the police leadership believed that legal limitations to randomly stopping vehicles, including potential liability, prevented their participation," the document said.
While federal officials contend the survey is voluntary, that's not entirely the case. Survey-takers use a device, called a passive alcohol sensor, to collect a breath sample before the motorist's "consent or refusal of the survey," according to the methodology. That lets researchers maximize the amount of data they collect while helping them get impaired drivers off the road, the document said. Later on, motorists are asked to blow into another device that measures blood-alcohol content more precisely.
Kim Cope said there was nothing voluntary about her experience with the survey last November.
Cope was heading out on her lunch break when she was funneled into a single lane of traffic, then directed into a parking lot by a uniformed Fort Worth, Texas, police officer. Cope agreed to take a breath test because she thought it would get her out more quickly, but she wasn't happy about it.