One of the most common complaints we hear from opponents of voter ID laws is that such rules would suppress voter turnout and make it more difficult for people to get to the polls. But for states who have already enacted such legislation, has the predicted effect proven true? Are there really less people making it out to cast their ballots on Tuesday? The Wall Street Journal takes a look at the question this weekend and finds that it’s not exactly an easy calculation to make.

Voters in more than two dozen states next month will be asked to provide some form of identification before casting a ballot. How many Americans who would otherwise vote will be turned away or won’t turn up at all remains a hotly contested number.

Some researchers have tried to count the number of voters affected, by surveying people about whether they have the required ID. This has produced a wide range of results, though, and some researchers question whether people whose IDs aren’t valid are aware of it, and whether they would rectify the situation if their state passed a tough ID law.

Just as with any other sort of predictive analysis based on a combination of public polling and sifting through data which is frequently ambiguous at best, several studies cited in the article were unable to make a definitive case in either direction. It remains an impossible task for us to ever predict what “would have happened” if some other hypothetical set of conditions existed. And for the data we do have, the requirement for some form of voter ID – or the lack thereof – is only one of many factors which determine how many people will show up to vote. The appeal of the candidates, the state of the economy… even the weather can all be big factors. The only two states with voter photo ID laws before the last presidential election – Georgia and Indiana – actually saw a sharp uptick in voter turnout, but that was compounded by what they describe as “an historic election” and an unusually high level of minority voter participation.

This left one analyst throwing up her hands.

Lorraine C. Minnite, a Rutgers University political scientist and a senior fellow at Demos, a liberal think tank, looked for a turnout effect in a 2009 paper she co-authored with Columbia University political scientist Robert S. Erikson. They didn’t turn up definitive evidence, concluding, “our data and tools are not up to the task of making a compelling statistical argument for an effect.”

Whether the inability to find an effect means there is no effect is contentious. To Prof. Minnite, it means the tools aren’t sharp enough, not that ID laws don’t curb voting.

Another item which can’t be quantified into hard numbers but which is acknowledged by these studies is the question of how likely the people most affected were to vote anyway. The majority of those without any form of photo ID were people who were apparently not all that big into participating in the public forum in the first place. This doesn’t mean that we should actively seek to stop them from voting – quite the opposite – but it does make it all the harder to figure out what the final effect of these laws are on turnout.

I still maintain that any such law should be enacted in a way that doesn’t put a direct fee in the way of someone being able to register or vote. That flies in the face of the constitution. But we also can’t allow ourselves to fall into the trap of eliminating any proposal which requires even the slightest additional effort to vote. Participating in virtually every aspect of our society requires some measure of effort. And if your state requires you to have a free photo ID – assuming you don’t have one of the most common ones already – then that’s an effort you’ll need to make. It takes an effort to get up off your couch and go to the polls anyway.