Arguments against public preelection polls charge that they influence voter behavior. Voters may decide to stay home if the polls predict a landslide—why bother to vote if the result is a foregone conclusion? Exit polls are particularly worrisome because they in effect report actual election results before the election is complete. The U.S. television networks agree not to release the results of their exit surveys in any state until the polls close in that state. If a presidential election is not close, the networks may know (or think they know) the winner by midafternoon, but they forecast the vote only one state at a time as the polls close across the country. Even so, a presidential election result may be known (or thought to be known) before voting ends in the western states. Some countries have laws restricting election forecasts. In France, no poll results can be published in the week before a presidential election. Canada forbids poll results in the 72 hours before federal elections. In all, some 30 countries restrict publication of election surveys.

The argument for preelection polls is simple: democracies should not forbid publication of information. Voters can decide for themselves how to use the information. After all, supporters of a candidate who is far behind know that fact even without polls. Restricting publication of polls just invites abuses. In France, candidates continue to take private polls (less reliable than the public polls) in the week before the election. They then leak the results to reporters in the hope of influencing press reports.

One argument for exit polls is that they provide a means for checking election outcomes. Discrepancies between exit polls and reported election outcomes invite investigation into the reasons for the differences. Such was the case in the 2004 presidential election. Were the exit polls flawed, or were the reported election results in error?