Whether the various new voter-ID laws have a significant effect on voter turnout has been notoriously difficult to assess empirically. The recent election results from Texas, however, might provide a way to get some insight into this question not previously available before.  As a result of federal court litigation, Texas now provides something of a natural experiment to test this question.

Up until now, it has been possible to get data in various states on the number of eligible voters who appear to lack the required forms of identification (typically, photo IDs) that a state’s recent voter ID law now requires.  Those numbers have often been established in litigation.  But the problem in understanding what effects these laws might have on election turnout and outcomes is that we do not know how many of those voters would actually have turned out to vote whether or not the voter ID law was in place.  The voters who lack the relevant IDs tend, not surprisingly, to be from socio-economic groups that have the lowest voter turnout rates as a general matter (in 2012, 47% of those earning under $10,000 voted while 80% of those earning more than $150,000 did, and see today’s NYT story on non-voters in Milwaukee).

Texas enacted what the federal courts declared to be the “strictest law in the country” governing in-person voter identification.  After declaring that law invalid, the courts ruled that the remedy for this election was that anyone who showed up at the polls without any of the relevant IDs could still vote and cast a regular ballot (not a provisional) by signing a form in which they stated that they had a “reasonable impediment” that made them unable to possess or get one of the relevant IDs.  So in this election, Texas essentially had two groups of voters who cast ballots, as the Texas Tribune noted:  those who had the relevant IDs and those who did not but signed the reasonable impediment forms.  The form can be found here.

I am not aware of any centralized data base for the number of “reasonable impediment” forms signed in Texas this election.  Once some enterprising journalist or social scientist tracks those numbers down, we will have a count of the number of voters who turned out but lacked any of the required IDs under Texas’ strict identification law.  Indeed, to the extent the litigation remains pending in the federal courts, these numbers could come out there.

Of course, this number will be an imperfect measure of how many actual voters this strict voter ID law would have blocked, but for the court-ordered option of voting with this form.  Eligible voters who lacked the IDs might have been deterred from showing up at all, because they did not know they could vote by signing these forms.  Perhaps some number of people showed up without IDs, but left because they were reluctant to sign the forms.

Determining the reason(s) people who did not show up to vote at all failed to do so will almost always be an impossible task.  But the count of these reasonable impediment forms will tell us how many people did show up to vote who would not have been able to vote had the Texas ID law been in effect without the court-ordered remedy in place that permitted these people to vote by signing this form.

Just to be clear, no individual eligible voter should be deterred from voting by unnecessary or unjustifiable barriers to voting.  But for those trying to gauge the systemic effects of laws like that of Texas,  Texas has just inadvertently enabled a useful social-science study.