Even before the sudden death of Justice Antonin Scalia, this was going to be an enormously consequential Supreme Court term.
The court has heard or has agreed to hear cases involving the constitutionality of considering race in college admissions, how far states can go in restricting abortion, the viability of public sector unions, whether President Barack Obama could defer deportations of unauthorized immigrants and the tension between claims of religious freedom and women's access to contraception.
The high court recently stepped in to halt implementation of Obama's climate plan.
Now, all of the cases on the court's docket are thrown into question, particularly as top Republicans like Senate Majority Leader Mitch McConnell have declared that the Senate should wait to confirm a replacement until a new president is in office.
If the court of eight justices splits 4-4, the opinion of a federal appeals court stands without making law for the rest of the country, according to Samuel Bagenstos, a law professor at the University of Michigan who clerked for Supreme Court Justice Ruth Bader Ginsburg and has argued before the court several times.
The justices generally vote for a case's outcome at a conference after oral argument, after which the chief justice assigns an opinion — but if Scalia was the deciding fifth vote in a case that has already been heard, that result is negated.
"Unless a justice is sitting at the court at the time of argument and at the time the decision is issued, the justice's vote doesn't count," Bagenstos said.
Democratic presidential candidate Hillary Clinton raised that issue Sunday in Las Vegas, telling a gathering of immigrants in the country under Obama's immigration program that "we have a president, he was elected, he has the right to nominate another Supreme Court justice."
Clinton referred to the 5th U.S. Circuit Court of Appeals' vote to temporarily block Obama's executive action to defer deportations of some undocumented immigrants, which the high court is expected to hear in April.
Clinton sent her condolences to Scalia's family and then observed that "because of his passing, there will be most likely a tie, 4 to 4, on important issues that affect so many people in our country — and one of the most important is the decision about President Obama's actions" on immigration."
Clinton called the appeals ruling "a bad decision," saying, "I believe President Obama had the authority to do what he did."
Scalia's death may not make a difference in Fisher v. Texas, the affirmative action case brought by Abigail Fisher accusing the University of Texas for discriminating against her for being white.
Justice Elena Kagan recused herself from that case, having worked on it as solicitor general. That means that if Justice Anthony Kennedy votes to strike down Texas's affirmative action policy, as many expect him to, the result will likely be a 4-3 majority, Bagenstos said.
In cases before the high court, appeals courts have already ruled in favor of unions, upheld a controversial Texas abortion law, blocked a plan to shield millions from deportation, and against religious groups seeking to avoid having to provide contraception to employees.
In the case heard Jan. 11 that was expected to gut public sector unions, Friedrichs v. California Teachers Association, the 9th U.S. Circuit Court of Appeals ruled for the unions.
The issue before the court is whether state employees who choose not to join a union must still pay a share of union dues to cover contract negotiations and other benefits.
In Whole Woman's Health v. Hellerstedt, the court's biggest abortion case in decades, the 5th U.S. Circuit Court of Appeals ruled against the abortion clinics in upholding parts of a Texas law requiring doctors performing abortions to have admitting privileges at nearby hospitals. It resulted in the shutdown of dozens of abortion clinics.
The group of religious nonprofits before the Court in a case consolidated as Zubik v. Burwell, who object to the Obama administration's plan for providing contraception to women whose employers object, all lost at their respective lower courts, though other organizations not technically before the Court prevailed at the 8th U.S. Circuit Court of Appeals.
Another possibility, said Bagenstos, is for the cases to be re-argued in the next term. But, he said, “In the absence of new justice joining the court, that would be very unlikely."