The National Highway Traffic Safety Administration's national office is just a few miles southeast of Loudoun County in Washington D.C. It's there that the federal agency has worked since 1970 to improve highway safety.
A recent NHTSA national survey of drivers' alcohol and drug use shows that the use of alcohol among drivers is on the decline. The survey conducted in 2013 and 2014 shows that just 1.5 percent of weekend drivers had blood alcohol levels at or above Virginia's legal threshold of 0.08 percent.
That's a drop of 80 percent in drivers measured at or above the legal limit since testing began in 1973.
The survey also showed that 8.3 percent of weekend drivers had any alcohol whatsoever in their systems. That figure represents a huge drop of 77 percent since the surveys began 42 years ago.
However, the NHTSA was quick to point out that not all impairment trends are positive. The percentage of weekend drivers with illegal drugs detected in their systems was 15.2 percent, while the percentage of drivers with OTC (over the counter) drugs that could impair driving was at 7.3 percent.
The most popular drug of all among weekend drivers? Marijuana, which showed up in 12.6 percent of drivers. That figure represents a whopping increase of 47 percent of drivers who tested positive for THC (the active ingredient in marijuana) in 2007.
When it comes to police officers determining that a driver is impaired, it doesn't much matter what the driver's choice of substance might be. Impairment is impairment and the driver will face a DUI charge regardless. An arrest sets the criminal justice system in motion, making it imperative for the driver to get help from an attorney with experience in DUI defense.