Richard Wolf

USA TODAY

WASHINGTON — For nearly four months, the most important number at the Supreme Court has been eight. Now in the waning days of a most unusual term, the numeral to watch is three.

Eight is the number of justices struggling to decide cases following Justice Antonin Scalia's death in February. The difficulties posed by that even number have dominated the court's business — prompting several tie votes, some compromise rulings on divisive issues and more caution in granting cases for next term.

But not all cases can be dismissed, delayed or denied, and the court now faces three issues of huge social importance: Abortion, immigration and affirmative action.

Those are the highlights from among 19 cases left to be decided before the end of June. They include a second tier of closely watched cases, including one that could set a higher bar for public corruption, another that could help ease Puerto Rico's crushing debt and a third that could affect drunk drivers who refuse breath or blood tests.

The justices could rule in any of the Big Three cases as early as Monday:

Affirmative action. A former white student's challenge to the University of Texas' use of racial preferences in admissions dates back the longest. The case was heard in early December, after being returned to the Supreme Court for a second go-round. In 2013, the justices demanded tougher judicial scrutiny of the school's use of race, but an appeals court again sided with UT.

Supreme Court skeptical of racial preferences in university admissions

Unlike the other cases, this one will be decided by just seven justices, because Justice Elena Kagan has recused herself after working on it as U.S. solicitor general. Without the risk of a tie, advocates and opponents of affirmative action anticipate a ruling for or against the policy — perhaps with repercussions for other universities as well. The betting line tilts slightly against UT.

Abortion. Another case from Texas challenges a state law that imposed major restrictions on abortion clinics, ostensibly to protect women's health. The law requires clinics to meet the same standards as ambulatory surgical centers and forces doctors to have admitting privileges at nearby hospitals — rules that threaten to leave only nine fully functioning abortion clinics in a state with 5.4 million women of reproductive age.

Supreme Court closely divided on abortion case

Two lower federal courts have upheld the law, but abortion rights proponents say it places too great a burden on women seeking abortions, without a justifiable health benefit. They may have a winning hand if Justice Anthony Kennedy joins the court's four liberals against one or both restrictions. A substantive ruling could represent the most significant abortion decision by the court since 1992.

Immigration. Case number three from Texas is President Obama's effort to overturn lower court rulings that have blocked him from offering more than 4 million undocumented immigrants a chance to remain in the country without fear of deportation. It represents his last chance to help the parents of those brought to the country as children who have already won such a reprieve.

Supreme Court split on Obama immigration plan

Texas led a group of 26 states against the plan, complaining that it would have to pay for driver's licenses if the parents dodge deportation proceedings. Obama's best chance appears to be the hope that a majority of justices will decide the cost of licenses does not give Texas sufficient standing in court. Otherwise, a 4-4 tie would uphold the verdict of the lower courts, and the program would be dead.