The findings are notable because they're some of the first using data in elections that took place after some states implemented photo ID requirements to vote. Previous studies on the effects of these laws showed mixed results. A 2014 report by the Government Accountability Office examined 10 of these studies. Five showed no significant effect of voter ID laws on turnout, four found a significant decrease in turnout, and one found, paradoxically, that the laws increased turnout.
But each of these 10 studies was of general elections that took place before 2008. Most of the strictest ID laws were passed after that, so the ability of earlier research to gauge the impact of these laws is extremely limited.
That's what makes the current research so important. The study's authors controlled for a wide variety of factors known to affect voter turnout -- age, education, income, marital status, etc.
They also controlled for other state laws that affect participation, like early voting. And they considered less-tangible aspects that influence turnout, like the competitiveness of races and whether the election was held during a presidential contest year or an off-year.
After controlling for all these factors, they found "substantial drops in turnout for minorities under strict voter ID laws." Their analysis suggests that turnout for Latino voters was suppressed by 10.8 points in states with strict photo ID laws, compared to states without them. For multiracial Americans, the drop was 12.8 points.
The laws also increased the participation gap between whites and non-whites. "For Latinos in the general election, the predicted gap from whites doubled from 5.3 points in states without strict photo ID laws to 11.9 in states with strict photo ID laws," the study found. For black voters in the primaries, the strict photo ID laws caused the gap with white voters to almost double to 8.5 points.
The net effect of all this? "Democratic turnout drops by an estimated 7.7 percentage points in general elections when strict photo identification laws are in place." Democrats weren't the only ones affected, either. The data showed that Republican turnout was depressed by 4.6 percentage points too.
This makes sense, as Voter ID requirements are a poll tax, affecting those who don't have transportation, time, money, or the ability to produce the necessary documents in order to get a valid form of identification. Yes, poor Republican voters were going to be disenfranchised too under these laws...but not nearly as many Democrats and especially black and Latino Democrats.
And I'm betting Republicans are more than happy to lose 4.6% of their voters in order to cost Democrats 7.7% of theirs. This was the point all along, and both parties know it.