The U.S. Supreme Court typically reserves its most controversial or impactful opinions for later in the term. This year, affirmative action cases — usually as controversial as any cases the justices will hear — were released first, so the pending student loan cases could be held for the final day. While the debate concerning the extent to which race ought to be considered in college admissions (and potentially employment and other settings) is complex and continually evolving, the debate over student loans seems on its surface to be a much more binary question: Can the executive engage in mass loan forgiveness without the permission of Congress, or not?

Just hours after the Supreme Court issued its ruling in Biden v. Nebraska , President Joe Biden himself delivered remarks asserting that his administration would engage in negotiated rulemaking to deliver on his campaign promise of providing student debt relief, a process likely to take a year or more. However, with its ruling , the court joined bipartisan majorities in both houses of Congress in affirmatively rejecting this plan. This alone makes it clear that the loan forgiveness fight is not only far from over, but could potentially culminate in a more direct confrontation between the judicial and executive branches.

While it seemed likely based on oral arguments that the court would decide against the Biden administration (particularly if standing were granted), an arguably more significant question loomed: Would the scope of the decision be limited to Biden’s use of emergency authority in the HEROES Act of 2003 or something broader? We now know that the court’s decision was expansive and could impact not only the forgiveness plan, but also the administration’s promised rebuttal actions, their even more significant income-driven repayment (IDR) changes , and more.

In his majority opinion, Chief Justice John Roberts quoted from and built upon the Court’s landmark decision curbing executive authority in West Virginia v. EPA :

If it is “inherent” that Congress would want the ability to decide whether to issue vast loan forgiveness, one would expect that the court’s decision would at least put the administration on notice about any of its future plans. Still, loan forgiveness continues on two tracks: the just-announced rulemaking on forgiveness itself and the IDR rulemaking already well underway to substantially reduce repayment obligations and then grant borrowers forgiveness after a number of years (regardless of what balance may remain). The former is a political gesture that may never see the light of day.

The Biden Team likely views positively the fact that the process to enact it will take a long time, easily extending it into the heart of their reelection campaign. For now, the Biden administration continues to spend wildly on still more loan forgiveness efforts, including approximately $5 billion per month to support the ongoing student loan pause until it expires in September. Ultimately, it could be challenged in court and bring about a fresh legal battle.

The administration’s IDR program is even more likely to generate a challenge. While the court’s ruling in Biden v. Nebraska calls both policies’ legality even further into question, standing to sue may be an even greater challenge with IDR. And while many in the press remain focused solely on forgiveness, IDR is likely to have a far greater impact if actually enacted. Its cost was already estimated to easily be in the hundreds of billions of dollars, but many of the same dollars that could have been forgiven through the original loan forgiveness might now be just as easily forgiven through IDR.

IDR is also a backdoor method of achieving Biden’s campaign proposal for “free community college,” since low earners with low loan balances have a particularly high likelihood of paying little to nothing until they have their balances forgiven. This prospect could encourage the numerous two-year institutions that do not currently participate in the loan program to jump in with both feet, expanding the cost even further.

All further reasons why the IDR proposal is the key facet of this issue to watch. In the coming months, it will be enacted, legal challenges will immediately follow, and the biggest question will once again prove not to be whether the Biden administration truly has the constitutional authority to enact a mass loan forgiveness program, but whether anyone has the ability to stop them.

“The ‘economic and political significance’ of the Secretary’s action is staggering . . . . And the Secretary’s assertion of administrative authority has ‘conveniently enabled [him] to enact a program’ that Congress has chosen not to enact itself . . . . All this leads the Court to conclude that ‘[t]he basic and consequential tradeoffs’ inherent in a mass debt cancellation program ‘are ones that Congress would likely have intended for itself.’”

This article originally appeared in the AEIdeas blog and is reprinted with kind permission from the American Enterprise Institute.