The November presidential election, widely expected to rest on a final blitz of advertising and furious campaigning, may also hinge nearly as much on last-minute legal battles over when and how ballots should be cast and counted, particularly if the race remains tight in battleground states.

In the last few weeks, nearly a dozen decisions in federal and state courts on early voting, provisional ballots and voter identification requirements have driven the rules in conflicting directions, some favoring Republicans demanding that voters show more identification to guard against fraud and others backing Democrats who want to make voting as easy as possible.

The most closely watched cases — in the swing states of Ohio and Pennsylvania — will see court arguments again this week, with the Ohio dispute possibly headed for a request for emergency review by the Supreme Court.

In Wisconsin, the home state of the Republican vice-presidential candidate, Representative Paul D. Ryan, the attorney general has just appealed to the State Supreme Court on an emergency basis to review two rulings barring its voter ID law. But even if all such cases are settled before Nov. 6 — there are others in Florida, Iowa and South Carolina — any truly tight race will most likely generate post-election litigation that could delay the final result.