With millions of Americans turning out to cast their ballots on Tuesday and the latest polling still showing a down-to-the-wire race, we should all hope that whichever candidate wins the presidential contest, he does so with a decisive and uncontestable margin. Otherwise, we could face contentious recounts, unprecedented litigation, and a long delay in knowing who our next President will be.

Very close elections pose two dangers. One of those dangers was expressed by the Supreme Court in 2008 when it upheld the constitutionality of Indiana’s voter ID law. The Court noted that the United States has a long history of voter fraud that had been documented by journalists and historians and that such fraud “could make the difference in a close election.”

When we remember that the 2000 presidential race was decided by only 537 votes, it is not hard to imagine a scenario in which some might be tempted to engage in election fraud to help their favorite candidate, particularly in a state where the race is too close to call. That willingness to break the law for political advantage was certainly illustrated in the recent undercover video of the son of a Virginia congressman telling an undercover reporter how to cast fraudulent ballots in the names of registered voters. John Fund and I illustrate other examples of such fraud in our new book, Who’s Counting? How Fraudsters and Bureaucrats Put Your Vote at Risk.

But another troubling scenario in a very close election is the potential fight over provisional ballots. When Congress passed the Help America Vote Act in 2002, one of the requirements of the new law for all federal elections was provisional ballots. Provisional ballots must be provided to any individual whose eligibility to vote is questioned or challenged at the polls. These ballots are kept separate from the regular ballots cast by registered voters. They are examined and reviewed by local election officials during the week after election day. In each case, election officials investigate the circumstances and make a determination of whether the voter was in fact eligible and registered to vote and whether that ballot should be counted.

Provisional ballots were a beneficial development in the law because they prevent a voter from losing his right to vote if there is some kind of administrative mistake by state officials. One of the most common errors is when an individual registers to vote at a state driver’s license bureau but the DMV fails to forward the registration form to local election officials. Under such circumstances, the provisional ballot should be counted.

But you are not entitled to have your provisional ballot counted if you make a mistake as a voter, such as someone who is eligible to vote but who fails to register as required under state law. Provisional ballots were not intended by Congress to be an end run around state registration requirements.

The number of provisional ballots cast in some states number in the hundreds of thousands. If the number of provisional ballots in a state exceeds the margin of victory of one of the candidates, a contentious fight could ensue, especially if the outcome could determine the presidency. It is likely you would have lawyers from both campaigns reviewing (and contesting) every decision made by local election officials on every provisional ballot, similar to what happened with punch-card ballots and the infamous chad problem in Florida in 2000. We could experience Florida-style litigation over the provisional ballots repeated in numerous states.

Let’s all hope we have a smooth, fair election with a sure winner at the end of the evening, rather than a long fight over the outcome from which only the lawyers involved will profit.