Washington (CNN) The Supreme Court on Monday sidestepped two major cases concerning partisan gerrymandering, allowing controversial district maps to stand and be used in this fall's midterm elections.

The 9-0 ruling authored by Chief Justice John Roberts in a Wisconsin case is a blow to Democrats who argued the Republican-drawn maps prevented fair and effective representation by diluting voters' influence and penalizing voters based on their political beliefs.

While the ruling will let the maps be used, the justices dodged the question of whether they are legal. The Supreme Court has a standard limiting the overreliance on race in map-drawing, except under the most limited circumstances. The court has not been successful in developing a test concerning the overreliance on politics.

Democrats had won a challenge in a lower court, but the Supreme Court's decision Monday would limit who can bring such cases in the future.

The second case was out of Maryland, where Republicans challenged a district map drawn by Democrats. The justices said that a lower court did not act improperly in leaving the map in place.

In an unsigned opinion with no dissents, the justices said that the challengers failed to reach the high bar of showing "irreparable harm" that would be necessary for a preliminary injunction to block the map.

"Even if we assume -- contrary to the findings of the District Court -- that plaintiffs were likely to succeed on the merits of their claims, the balance of equities and the public interest tilted against their request for a preliminary injunction," the court said.

The court's opinion in Maryland case means that for now the justices will leave having to answer whether the court can set a standard for when politicians go too far in drawing lines to benefit one party over another for another day.

Roberts sends Wisconsin to lower court

Roberts walked a fine line in his opinion in the Wisconsin case, finding the challengers did not have the legal right to bring the case.

Under normal circumstances, Roberts wrote, "we usually direct the dismissal" of the case. He added, "This is not the usual case."

The court opted instead to send the case back to the lower court so the challengers might have another chance to "prove concrete and particularized injuries" by showing there had been a burden on their individual votes. That showing, in turn, would allow the challengers to proceed to the merits of the case.

That could be the reason Roberts got the liberals to sign on. Many believed the justices might use "standing" -- or the legal right to bring a case -- as an off ramp to avoid the merits in the case.

But few believed the opinion would be unanimous.

Roberts stressed that "we express no view on the merits of the plaintiffs' case." But he also cautioned that such challenges might be hard to bring down the road.

He noted that how the challengers bring these cases is key.

"It is a case about group political interests, not individual legal rights," he wrote. "But the Court is not responsible for vindicating generalized partisan preferences. The Court's constitutionally prescribed role is to vindicate the individual rights of the people before it."

Liberals wanted court to act

While the liberals on the court agreed with the decision to send the Wisconsin case back down to the lower court, they emphasized that the court should someday take up such cases.

"Partisan gerrymandering no doubt burdens individual votes, but it also causes other harms," Justice Elena Kagan wrote.

She called partisan gerrymandering "incompatible with democratic principles."

There is a separate and similar challenge in the pipeline coming out of North Carolina, and the court could decide soon whether or not to hear that case.

"Courts -- and in particular this court -- will again be called on to redress extreme partisan gerrymanders," Kagan wrote. "I am hopeful we will then step up to our responsibility to vindicate the Constitution against a contrary law."

Elizabeth Wydra, president of the Constitutional Accountability Center, told CNN that Kagan's concurrence showed "the substantive battle over the constitutionality of partisan gerrymandering is far from over."

Wydra said there does not appear to be five votes on the court to say definitively the courts must stay out of partisan gerrymandering.

Kennedy most silent

"Most likely Justice Kennedy's vote is still in play when a case gets to the court with the right plaintiffs and the right theory of harm," Wydra said. "And Kagan's concurrence today makes a powerful case to Justice Kennedy that when that case comes, he should recognize that partisan gerrymandering is incompatible with the Constitution and democratic values."

On Monday, Justice Anthony Kennedy stayed relatively silent. The last time the Supreme Court heard a major partisan gerrymandering case, in 2004, four conservative justices said the issue should be decided by the political branches, not the courts. But Kennedy was unwilling to bar all future claims of injury from partisan gerrymanders.

Before Monday's decision, court watchers thought Kennedy might have found a standard that courts could use when deciding when states go too far in using politics to draw state lines. But not only did he refrain from writing separately, he also declined to join the concurring opinion put forward by the liberals.

Democrats, advocacy groups weigh in

After the ruling, Paul Smith, a lawyer for the challengers in the Wisconsin case, said "the case is very much still alive."

"We now have the opportunity to demonstrate the real and concrete harms that result from partisan gerrymandering in the lower court, the same court that struck down the Wisconsin mapping scheme to begin with," he said.

Wisconsin Democrats issued a statement via Twitter in response to the Supreme Court, vowing to continue their fight in face of the decision.

"The fight for fair maps did not end today," the party's statement read.

Our response on the Gill v. Whitford decision: pic.twitter.com/X9ZZC2CKgk — Democratic Party WI (@WisDems) June 18, 2018

Wisconsin Attorney General Brad Schimel issued a statement that touted the court's decision but did not comment on the fact the court had sent the case back instead of dismissing it all together.

"I am pleased that the highest court in the land has unanimously reversed the trial court's erroneous decision invalidating Wisconsin's Assembly map," Schimel, a Republican, said. "Today is win for the rule of law in Wisconsin, and a testament to the talented attorneys at the Wisconsin Department of Justice."

Advocacy groups fighting against political gerrymandering likewise weighed in.

The American Civil Liberties Union called the Supreme Court's punt on Monday a "missed opportunity," although there are ongoing cases in Ohio and North Carolina.

And Kristen Clarke, president of the Lawyers' Committee for Civil Rights Under Law, said the court "failed to provide long-awaited resolution and clarity on what constitutes unlawful gerrymandering."

"As the case is now remanded to the district court for further development of the facts, we will remain vigilant to ensure that officials do not exploit this moment to alter redistricting maps in ways that undermine democracy," Clarke said.