Wednesday, September 19, 2018

Are DWI fatalities "out of control" or "curiously constrained"?

At the Houston Chronicle, St. John Barned-Smith and Dug Begley have an extensive feature on DWI in the Houston metro area, noting that the Houston and Dallas metro areas have the most DWI fatalities of any in the country since the turn of the century.

This is less reporting than an advocacy piece, making the argument that, in the authors' words, "Texas is not doing enough to stop impaired drivers."

Grits doesn't mind a good advocacy article; after all, that's precisely what I do here. But I mention it to emphasize that their premise that Texas isn't doing "enough" is a normative declaration, a value judgment rather than a data-based observation. These authors have declared themselves the arbiters of what is sufficient.

Moreover, since this is an advocacy piece, it doesn't necessarily provide facts that might dispute its thesis, and frames data (e.g., as a 16 year aggregate rather than annualized trends) in ways that support their argument, while omitting frames that might not. In Grits view, the situation is more complicated than portrayed.

For example, while the graphic above is intended to lead to alarm that Dallas and Houston have more deaths over this 16-year period than the New York City MSA, drivers in Texas spend much more time on the road than New Yorkers. E.g., this source announces that in 2011, licensed drivers in Texas averaged 16,347 miles driven each, compared to 11,871 for each New Yorker. Might that have something to do with the difference in alcohol-related traffic-death totals?

Also, the authors, having established themselves as the Arbiters of Enough, suggest that law enforcement is failing to deploy sufficient officers to combat DWI. "Law-enforcement leaders deploy inadequate numbers of officers to drunken-driving enforcement," they opine. And depending on what you think is "enough," the data on DWI arrests may even, on the surface, seem to corroborate that suggestion.

The chart at left is from the Office of Court Administration's Annual Statistical Report for 2017. It shows that DWI enforcement has declined significantly in recent years, with felony DWI cases dropping 24 percent over the last five years and regular DWI cases dropping 13 percent. Overall, police are making half as many DWI arrests than they were thirty years ago, when the state's population was much smaller.

So cops are arresting fewer people for DWI, and indeed traffic enforcement overall has plummeted, as evidenced by this OCA graphic at right:

FWIW, since traffic enforcement has declined even more than DWI enforcement, that tells us that police departments have continued to prioritize DWI, even as traffic enforcement declined, perhaps to a greater degree than the authors gave credit. These data indicate to me that DWI enforcement is not just something that's incidental to regular traffic enforcement, in other words, but has continued to be prioritized, even as traffic enforcement overall was de-prioritized.

But the data that most make me question the assumptions behind the writers' "more enforcement" recommendation is that, during this period of declining enforcement, which coincided with a massive population boom and more cars on the road than ever, Texas DWI deaths remained roughly steady, appearing to be unaffected by either the influx of drivers or the radical decline in enforcement. In fact, they even declined slightly.

Using data from the Texas Department of Transportation, Grits created this chart showing the annual breakout of DWI-related deaths since 2010:

When you consider that Texas' overall population grew by 12 percent over the same period, the trend, to this writer, doesn't seem quite so alarming.

To be sure, one DWI fatality is too many and the state has a big interest in preventing them. The point here is that the evidence in these charts doesn't indicate that DWI enforcement on the roadways plays a big role in reducing fatalities. After all, with more people on the roads and much less enforcement, per capita DWI deaths remained relatively steady, even declining a bit over this period. So if we're looking at the most effective means of reducing DWIs, it's not obvious that devoting more personnel to patrolling the streets would help. When departments took those officers off of traffic patrol, there was no resulting climb in the number of traffic fatalities.

Grits would also ardently dispute the authors' contention that the state should suspend more drivers licenses. They inform us that:
A Chronicle survey of state laws pertaining to license suspensions and interlock use found Texas' were among the most lenient. Lawmakers in 36 states have established longer license revocations, suspensions or more lengthy interlock use than Texas. 
For repeat offenders, Florida can impose permanent suspensions. Florida does not allow suspension time to run while the offender is in prison.
But as regular Grits readers know, Texas has more drivers with suspended licenses than any other state in the country, so many, in fact, that the situation has contributed to massive lines at DPS license centers that can take as long as eight hours to navigate. The last thing we need to do is suspend more drivers' licenses for longer periods.

Anyway, as Clay Abbott, a prosecutors' DWI expert, told the authors, "Texas' sprawl means drunken drivers will get behind the wheel even if their license is suspended — they'll just do it illegally." That's what we've seen with the 1.4 million drivers - about 12 percent of them DWI offenders - whose licenses have been suspended for Driver Responsibility surcharges.

So, while there was some useful data and commentary in this feature story, I think the authors got a lot wrong. By aggregating data over 16 years instead of looking at annual trends, they failed to convey the cognitive dissonance over the fact that a decline in enforcement left DWI fatality numbers essentially unaffected. That blows big holes in their advocacy for deploying more police officers to make DWI arrests. We've just witnessed a natural experiment over the past few years showing the two things don't necessarily correlate.

And the authors' inchoate advocacy that Texas should suspend more driver licenses for longer strikes me as remarkably tone deaf to the political realities created by lines of drivers - many of them with suspended licenses - stretching around DPS license centers around the state. Texas needs to find ways to reduce license suspensions if they want to shorten license-center lines, not lard on more suspensions and worsen the problem.

The authors are also hot to trot over the creation of DWI traffic checkpoints, which are unconstitutional in Texas unless the Legislature explicitly authorizes them. While they do quote outgoing state Rep. Jason Villaba explaining why those measures haven't passed - "The kinds of things that can be done are the kinds of things that usually interfere with the rights of the people who are not engaging in the behavior" - the authors proceed to blow past those objections, giving the police chief the last word on the topic to insist, "Eventually we're going to get them."

None of this is to say DWI fatalities are not a major societal problem. But this Chron article was titled, "Out of Control." To me, that headline overstates things in a period when more drivers than ever were on the road, police enforced DWI laws less often, but per-capita DWI fatalities stayed the same or went down.

Not only does that not seem "out of control," given the counter-intuitive result where less enforcement had no discernible, upward effect on fatality numbers, Grits would instead characterize the dynamic as "curiously constrained."


Phelps said...

Whatever we do, make sure we don't correlate this with the hate facts in Table 3 of this report:

Anonymous said...

You’re failing to account for the single biggest factor in the falling number of DWI arrests: Uber, Lyft, ect.
Now that those services have taken hold, I’m curious what the numbers are going to do going forward.

He's Innocent said...

Does anybody else see a correlation to Chief of Police Art Acevedo's recent rants that his department needs more money, more officers, more everything? As he did here in Austin, Acevedo has a habit of blowing issues out of proportion to suit the needs of his ego. I agree with Grits' take on this, but wanted to add this nugget for thought.

Anonymous said...

Those reporters have weird names! Is "St. John" really somebody's first name? And "Dug"? Somebody send out a search party for that missing "o"!

Anonymous said...

Why doesn't Dallas have deep diving reporters like these? The great reporters seem to only live in Houston and Austin.

Anonymous said...

Anon 4:23

Never read Jane Eyre? Or seen "A View to a Kill?" -

Phelps said...

Dude, Dallas has Stephen Young. I'm pretty sure he gets a new keyboard every morning and ruins it by 4pm with drool.

Arce said...

One thing that might prevent some drunk driving, reducing the rate of injuries, would be to install breath analysis machines at popular drinking spots, so drivers could be tested prior to leaving the place.

Kuato said...

Yep - Got Art Acevedo's fingerprints all over it. He sees his primary job as using what tax payers pay him to promote propaganda that will get even more from the taxpayers. But what they get in return is not more 'safety' but less. Less safety from those he gets added to the standing army that is already eating out our substance. (to use the words of our DOI, 1776)

Anonymous said...

Conspicuously absent in the article is DPS. The State Troopers of the State Police agency should be patrolling the State Highways, some of which are highways of death like in the north of Houston.
It would be interesting to overlay the location of DPS traffic ticket locations with the DWI/fatal accident locations. State Troopers have that ticket quota, so they hang out at malls, strip centers, and other urban areas that are patrolled by county and municipal police, in order to get their easy ducks to meet that ticket quota. Instead they should be patrolling the super highways in the unincorporated areas that are killing people with speed and alcohol.

Will said...

..."Highways of death like in the north of Houston" implies you want Troopers to patrol that incorporated area, but later on you state "...they should be patrolling the super highways in the unincorporated areas..." Your argument is contradictory.