The Numbers Behind DWI Arrests

Last night’s fascinating report by KRQE’s Larry Barker on the trends (or lack thereof) behind DWI arrests in Bernalillo County should be required viewing for New Mexico politicians. Barker’s DWI timeline displays monthly arrests since 1991, highlighting key events in our ongoing battle against drunk driving. Barker’s conclusion? Tighter enforcement and stricter penalties are not reducing the number of drunk drivers arrested.

The DWI Resource Center and Steven Flint’s have compiled and posted on the web a treasure trove of traffic safety data from NM Motor Vehicle Division records. Looking at yearly data over a twenty year period, 1985-2005, we can take a more thorough look at any trends, not just for Bernalillo County but also state-wide, and hopefully offer a more conclusive analysis than eye-balling a graph.
Applying some basic statistical tools, Larry Barker’s conclusion is affirmed. There has been no statistically significant change in the number of DWI arrests over the past two decades, not in Bernalillo County and not in the state as a whole. Statewide, DWI arrests have simply fluctuated up and down around a mean of 20,300 per year, a third of those (6,782 on average) in Bernalillo County.
Why are we making the same number of DWI arrests every year despite increasing penalties, banning drive-up windows, installing ignition interlocks, and saturating the airwaves with public education campaigns? Unfortunately, another key variable is showing a significant downward trend–the DWI conviction rate. Though the number of arrests has remained relatively stable, the number of convictions based on those arrests has dropped on average by a startling 129 per year statewide. In 1985, 74.8% of those busted for DWI in New Mexico were convicted, down to 62.5% in 2005. The problem is even more severe in state’s most populous county. Bernalillo County had 22 more DWI arrests in 2005 compared to 1988, but in 1988 we followed through on those arrests with 752 more convictions. Bernalillo County’s DWI conviction rate fell from 67.3% in 1985 to a shameful 55% in 2005, bottoming out (hopefully) at 49% in 2003.
Thinking about driving drunk in Bernalillo County? Why worry about harsher penalties if you’ve got even odds of getting off scot-free?
Another significant trend emerges that might help explain this pathetic conviction rate. While the number of DWI arrests has remained relatively stable, the number getting hearings has tripled, 30.2% statewide in 2005 up from 10% 1985, while in Bernalillo County the percentage granted hearings rose from 11.3% to 44.3%. Tougher penalties lead more people to seek hearings rather than simply paying a fine, and it seems our courts (and arresting officers) are being overwhelmed. Tougher penalties are only as good as our ability to dish them out, and in this we are failing. We shouldn’t have to wait for drunk drivers to become murderers for the justice system to treat them seriously.
But there is some good news in the DWI statistics. As Rachel O’Conner, New Mexico’s DWI Czar, pointed out in Larry Barker’s report, drunk driving is killing fewer New Mexicans than before. This is due to a significant overall reduction in the number of alcohol-related crashes. The percentage of DWI arrests made after accidents has fallen steadily from a statewide peak of 21.3% in 1988 to 15.4% in 2005, a trend mirrored in Bernalillo County. Although we’re making roughly the same number of DWI arrests per year, there has been an important shift in the timing of those arrests–New Mexico’s law enforcement officers, with the help of vigilant civilians, are catching more and more drunk drivers before they hurt people. Checkpoints and other measures on this front appear to be working. The result is nearly 1,100 fewer alcohol-related crashes annually in the state, nearly 400 fewer in Bernalillo County.
If our goal is simply to pull drunk drivers out of their cars before they maim and kill, we’re making progress, though we still have a long way to go. But if our goal is to stop drunks from getting on the road in the first place, it’s time to reevaluate our approach. Doing more to make sure those arrested for DWI face the consequences of their actions seems like a good place to start. The data suggests that making sure arresting officers show up at the courthouse will do more to solve our DWI problem then siccing those officers on bartenders and gas stations.