I first reported on the Pima County Sheriff's Department sobriety checkpoint program on labor day weekend of last year. Since that time, far more comprehensive numbers associated with the program have become available. These numbers encompass a 16 month time frame and two full holiday seasons. Unfortunately for the sheriff's department, the numbers reinforce what critics of checkpoint programs have been saying for years. Sobriety checkpoints are:
* Negligently ineffective at identifying & removing impaired drivers from the road
* Subject thousands of innocent travelers to intrusive searches and seizures
* Designed to intimidate and control a populace rather than protect it
* A gross misuse of public resources
Harsh words you say? Well, let's let the numbers speak for themselves.
Between labor day weekend of 2005 and the end of 2006, the Pima County Sheriff's Department averaged 3.75 suspicionless sobriety checkpoints every month for a total of 60. On average, each checkpoint lasted 2.93 hours and were manned by 12.8 deputies. A total of 36,798 vehicles were stopped absent reasonable suspicion of wrongdoing and after being stopped, officers demanded 995 drivers take a field sobriety test (FST). Out of those FST's, only 219 resulted in arrest for driving under the influence.
What this means is that deputies were wrong 80% of the time when they thought reasonable suspicion justified forcing a driver to take an FST. Additionally, the overall DUI arrest rate was a paltry 0.59%. Since every sobriety checkpoint stop represents a seizure under the meaning of the fourth amendment, 36,579 innocent drivers, not to mention passengers, were unreasonably seized by the sheriff's department during this 16 month time frame.
From the raw data provided, the following information can be quickly deduced:
* No DUI charges in 36,579 out of 36,798 stops
* 2.7% FST rate (all stopped vehicles)
* 77.9% negative FST result
* 0.59% overall DUI arrest rate
* 99.41% DUI innocence rate
* 0.42% non-DUI citation rate
* 2.93 hours/checkpoint
* 12.8 deputies/checkpoint
* 37.5 man-hours/checkpoint
* 3.6 arrests/checkpoint
* 10.3 man hours/DUI arrest
To put these numbers in context, I also looked at the total number of DUI arrests made from all enforcement activity over the same time period. Since a total of 2,058 DUI arrests had been made, sobriety checkpoints only accounted for 10.6% of them, despite the huge investment in man-power, resources, time and media coverage. What was even more telling however was that Pima County's checkpoint arrest rate was markedly similar to rates found around the country - approximately 0.6%.
Given this information and the nature of suspicionless checkpoints in general, it should be obvious that 0.6% is the hard core rate of die-hard drinkers on the road at any given moment in time. As such, the Pima County Sheriff's Department is undermining its effectiveness and legitimacy by targeting a general public already driving impaired free at the 99.4% level.
Statistics from Tennessee have already shown that traditional policing methods that base traffic stops on reasonable suspicion are over ten times more effective at identifying and removing drunk drivers from the road then sobriety checkpoints. The real question to ask here is how many drunk drivers were NOT identified and removed from the roads because law enforcement resources were too busy harassing the traveling public at suspicionless checkpoints.
The next segment of this ongoing investigation will highlight the funding sources associated with these unreasonably intrusive policing activities. In the meantime, additional information can be found here.
