The Supreme Court on Tuesday. (Win Mcnamee/Getty Images)

THE SUPREME Court on Tuesday made its two most significant moves since losing Justice Antonin Scalia, splitting 4 to 4 on a major case involving teachers unions and calling for a rare rebriefing in a blockbuster contraception case. In both instances, having a split court led to a decent outcome. Yet Tuesday’s news also showed why keeping the court understaffed for any significant length of time would be bad for the law, the court and the country.

The union case concerned whether California teachers who refuse to join public-sector unions can be required to pay union fees to support collective bargaining, as long-standing precedent and practice stipulate. Those challenging the system argued that it violates teachers’ free-speech rights, and the case became a locus for the internecine war between pro- and anti-union forces.

Because the court split 4 to 4, a ruling from the U.S. Court of Appeals for the 9th Circuit upholding California teachers’ current fee arrangements will stand. That is just as well: Though teachers unions deserve plenty of criticism for opposing important education reforms, the justices would have had to overturn long-standing precedent to side with the union’s critics. Barring an extraordinary legal case, elected lawmakers should be the ones making such a significant policy change.

But the split court’s ruling still leaves a cloud of legal uncertainty around the union fees issue, because only a majority of justices can set court precedent. The case offered an early glimpse of what is to come in an era in which the court cannot reliably act as a final arbiter, resolving legal disputes in a way that makes the law more predictable and, therefore, fairer.

One might argue that the justices should have tried harder to agree on a binding, majority ruling. That is what they appear to be doing in the contraception case. Religiously affiliated nonprofit groups object to providing birth control to their employees through their health-care plans, which the Affordable Care Act requires, and they reject a compromise the government has offered them. Instead of splitting 4 to 4 again, the justices proposed a different compromise that would require the nonprofits when they are contracting for coverage to do nothing more than tell their insurance companies they do not want to provide contraception coverage through the plans they pay for. Those companies would then independently arrange for birth control coverage with interested employees. Early signs indicate that this compromise would satisfy both sides.

We would like to believe that this sort of cooperation would be the norm on an eight-member court. But the contraception case is particularly well-suited to compromise. It is likely that, without a ninth justice, the court will more often deadlock on major cases, in which values are more fundamentally in conflict.

Even if we might agree with some of the results, a quarter of a presidential term is a long time to go without a full Supreme Court. Senate Republicans should consider Merrick Garland’s nomination immediately.