When States Fight: How the Supreme Court Keeps the Peace

Last updated 6 months ago. Our resources are updated regularly but please keep in mind that links, programs, policies, and contact information do change.

California and Arizona going to war over the Colorado River. New York blockading goods heading to New Jersey. These scenarios sound like alternate history fiction, but in the earliest days of the United States, open conflict between states was a real possibility.

The states under the Articles of Confederation were less a unified nation than a loose collection of semi-independent countries. They had competing interests, rival economies, and disputed borders. The Framers of the Constitution provided an innovative solution in Article III: a neutral judicial referee, the Supreme Court of the United States.

This system has evolved to manage complex water rights, environmental conflicts, and modern policy battles between states.

A More Perfect Union Needs a Referee

The chaos of the 1780s explains why the Supreme Court received unique power to hear cases between states. The Articles of Confederation established not a strong national government but a “firm league of friendship” among thirteen sovereign states. The central government—a single-branch Congress—was dangerously weak. It couldn’t regulate commerce, raise taxes, or compel states to follow its directives.

This design, born from fear of centralized authority after revolution against Britain, inadvertently created a system where states behaved like rival nations.

Economic Warfare Between States

One immediate source of conflict was economic warfare. States with major ports like Pennsylvania and New York leveraged their geographic advantage by imposing tariffs on goods passing through to neighbors. New Jersey found itself paying taxes to both New York and Pennsylvania for essential imported goods.

This led to retaliatory tariffs and trade restrictions as each state protected its own economic interests. These “tariff wars” created friction, stifled economic growth, and undermined the idea of a common American market.

Territorial disputes were equally dangerous. When the Constitutional Convention met in 1787, at least ten of the thirteen states were embroiled in serious conflicts over boundaries, land claims, and river rights. These weren’t abstract disagreements. In the colonial era, such disputes had erupted into actual violence, like the “New York – New Jersey Line War,” a series of raids and skirmishes lasting over half a century.

Under the Articles, the prescribed method for resolving these quarrels was creating ad hoc arbitral courts, a cumbersome and often ineffective process that did little to permanently settle tensions. The central government was too weak to enforce lasting peace.

States as Independent Nations

The states’ behavior as independent sovereigns extended to foreign policy. New York established its own treaty with the Iroquois Confederacy, and many states openly ignored provisions of the 1783 Treaty of Paris that ended the Revolutionary War.

This pattern—economic warfare, territorial disputes, and independent diplomacy—resembled the international system in Europe, where disagreements were settled through power politics, shifting alliances, and military force. The Framers recognized this trajectory was leading the United States toward collapse and dissolution.

Creating a federal judiciary with original jurisdiction over interstate disputes wasn’t a minor legal adjustment. It was a foundational act of nation-building, a direct response to the Articles’ failures. By establishing a permanent, mandatory, and binding judicial forum, Article III fundamentally altered relationships between states.

It transformed conflicts that would have been resolved by political power or force into “judicial questions” decided by rule of law. This mechanism was core to the Preamble’s promise to “insure domestic Tranquility.” It forced states to lay down arms and pick up legal briefs, transforming them from rivals in a fragile league into litigants within a single, unified federal system.

The Constitutional Fix

The solution to 1780s interstate strife was embedded in Article III, which establishes the judicial branch. The crucial language appears in Section 2, outlining federal judicial power: “The judicial Power shall extend… to Controversies between two or more States…”

This clause explicitly grants federal courts authority to hear these sensitive cases. The next paragraph specifies which federal court hears them first: “In all Cases… in which a State shall be Party, the supreme Court shall have original Jurisdiction.”

Understanding Original Jurisdiction

Two types of court jurisdiction matter here:

Original Jurisdiction is the authority to hear a case for the first time. It’s where the trial happens, evidence is presented, and decisions are made on facts. The Supreme Court acts as a trial court in these instances.

Appellate Jurisdiction is the authority to review lower court decisions. Most famous Supreme Court cases fall under appellate jurisdiction, reviewing rulings from federal circuit courts or state supreme courts.

By granting the Supreme Court original jurisdiction in cases between states, the Framers ensured these disputes would go directly to the nation’s highest court, bypassing all lower state and federal courts. This was deliberate—providing a forum of utmost stature and neutrality for resolving conflicts between powerful sovereign entities.

Making It Exclusive

The first Congress solidified this vision in the Judiciary Act of 1789, making the Supreme Court’s jurisdiction not just original but exclusive in controversies between states. This provision, now codified at 28 U.S.C. § 1251, means the Supreme Court is the only court in the United States that can hear such cases.

This combination of constitutional grant and legislative reinforcement reveals profound understanding of interstate conflict dangers. The Constitution provided power, but Congress, by making it exclusive, prevented “forum shopping”—where New York might try to sue New Jersey in a New York state court, an outcome carrying no legitimacy in New Jersey and only exacerbating conflict.

The exclusivity provision funneled the most politically explosive disputes into a single, neutral forum standing above any individual state’s interests, ensuring decisions would be seen as final and authoritative.

The Supreme Court protected this unique constitutional role from political interference. In Marbury v. Madison (1803), the Court established judicial review and declared that Congress couldn’t expand or contract the Supreme Court’s original jurisdiction as defined in the Constitution. This decision cemented the Court’s original jurisdiction as a direct and unalterable grant of constitutional power, safeguarding its essential function as ultimate arbiter of interstate disputes.

How a State Sues a State

When one state has a grievance against another, it can’t simply file a lawsuit like a citizen or corporation would. The process for bringing cases under the Supreme Court’s original jurisdiction is unique, reflecting the “seriousness and dignity” of disputes between co-equal sovereigns.

The first step requires asking permission. The complaining state must file a “motion for leave to file a bill of complaint”—a formal request for the Court to hear the case. This is critical gatekeeping. The Supreme Court’s exercise of original jurisdiction is discretionary, not mandatory.

The Court has repeatedly stated this power should be “invoked sparingly.” It examines motions to determine if issues are sufficiently important to warrant attention and ensure no other adequate forum exists to resolve disputes. Since 1960, the Court has denied hearings to nearly half the motions for leave to file original cases, preserving limited resources for the most significant national issues on its appellate docket.

The Special Master System

If the Court grants the motion and agrees to hear the case, its next crucial action is appointing a Special Master. The nine justices aren’t equipped to handle complex and time-consuming trial processes. Their institutional role is deciding profound questions of law, not sifting through mountains of evidence.

The Special Master is the Court’s solution to this practical dilemma. A Special Master is typically a highly respected and experienced individual, often a retired federal judge or law professor with deep expertise in the dispute’s subject matter, such as water law or property law.

The Court delegates immense authority to the Special Master, who effectively acts as trial judge. The Special Master’s duties include:

• Presiding over all pretrial proceedings, including discovery
• Receiving evidence and exhibits from both sides
• Conducting hearings and taking testimony from witnesses
• Ruling on motions made by parties

This process can be extraordinarily detailed and last many years. In the water rights dispute Florida v. Georgia, the evidentiary hearing before the Special Master involved more than 1,800 pages of testimony and 2,400 exhibits.

After exhaustive fact-finding, the Special Master prepares a comprehensive report for the justices containing detailed findings of fact and recommendations for how the Court should rule. At this point, the process shifts, and the Supreme Court begins acting in its more familiar appellate capacity.

States involved in disputes can file “exceptions” to the Special Master’s report—formal objections to the Master’s findings or recommendations. The final stage involves the nine justices themselves reviewing the complete record, including all evidence, the Special Master’s report, and states’ exceptions.

Lawyers for each state then present oral arguments directly to the Court in Washington, D.C. Following these arguments, justices deliberate and issue final, binding decisions carrying the full force of federal law.

A Brilliant Institutional Adaptation

This hybrid procedure is brilliant institutional adaptation. It allows the Supreme Court to fulfill its constitutional duty as trial court for states without compromising its primary mission as the nation’s ultimate court of appeals.

By outsourcing intensive fact-finding work to trusted Special Masters, the Court transforms complex trials into more manageable review processes. Cases arrive before justices in formats similar to appeals—detailed records, lower authority recommendations, and specific points of error to be argued—preserving the Court’s time, resources, and institutional character.

From Borders to Water and Beyond

The Supreme Court’s original jurisdiction docket provides a unique window into American history, reflecting the nation’s evolving challenges. Early disputes centered on drawing physical boundaries. As the country developed, conflicts shifted to allocating scarce resources like water. The industrial era brought concerns about cross-border pollution, and in the modern era, states have used this forum to wage battles over national policy and ideology.

Drawing the Line: Boundary Disputes

For much of the nation’s early history, primary conflicts between states involved the most basic question of sovereignty: where does one state end and another begin? The Supreme Court’s role was providing definitive and peaceful answers.

A modern example is the 1998 case New Jersey v. New York, which revolved around ownership of Ellis Island. While most people associate the island with New York, the dispute arose over who had sovereignty over the 24.5 acres of land artificially created through landfill since the late 19th century, dwarfing the original 3-acre island.

The legal battle hinged on interpreting an 1834 compact between the two states, which set the boundary line in the middle of the Hudson River but explicitly granted the original Ellis Island to New York. New Jersey argued the new, man-made land was built on submerged lands that had always belonged to New Jersey under the compact. New York contended its sovereignty extended to the entire expanded island.

The Ellis Island Decision

The Special Master appointed by the Court agreed with New Jersey, relying on the common-law doctrine of “avulsion,” which holds that a boundary doesn’t change when land is altered suddenly, as with landfilling, rather than through slow, natural accretion. The Supreme Court adopted the Special Master’s recommendation, declaring that New Jersey held sovereignty over all filled portions of the island.

The decision’s impact was both legally definitive and practically complicated. The official state boundary line now runs through several historic buildings on the island, including the main immigration hall. The Court acknowledged this inconvenience but refused to adjust the boundary for practical reasons, stating its role was interpreting the compact’s law, not rewriting it. If states wanted a more convenient border, they would have to negotiate it themselves and seek congressional consent.

The Thirst for a Scarce Resource: Water Rights

As the American West was settled and populations grew, conflicts over a new resource became paramount: water. In the arid West, rivers crossing state lines are the lifeblood of agriculture and cities, making their allocation a source of intense and recurring conflict.

In these cases, the Supreme Court developed the doctrine of equitable apportionment. Under this principle, the Court doesn’t simply apply one state’s water laws or another’s. Instead, it acts as a court of equity, seeking to achieve “fair and equitable division” of water that balances interests, harms, and benefits to all involved states.

Arizona v. California: Federal Authority Over Water

Arizona v. California (1963) was a monumental battle over the Colorado River, one of the country’s most contested waterways. For decades, states had fought over their shares. In its landmark decision, the Supreme Court ruled that normal equitable apportionment doctrine didn’t apply because Congress had already stepped in.

The Court held that the Boulder Canyon Project Act of 1928 created a comprehensive federal scheme for allocating the river’s water. This act gave the Secretary of the Interior authority to apportion water through contract execution, effectively superseding state laws and judicial apportionment. The decision was a powerful assertion of federal authority over critical interstate resources and remains the foundation of Colorado River governance today.

Florida v. Georgia: The High Bar for Proof

A more recent equitable apportionment case, Florida v. Georgia (2021), illustrates the high bar a complaining state must clear. Florida, the downstream state, sued Georgia, claiming excessive water consumption by Georgia’s agricultural sector during droughts caused low flows in the Apalachicola River.

Florida alleged these low flows increased Apalachicola Bay’s salinity, leading to catastrophic collapse of its historic oyster fishery. After years of proceedings, the Special Master recommended the Court deny Florida’s request to cap Georgia’s water use. The Supreme Court unanimously agreed.

Justice Amy Coney Barrett, writing for the Court, explained that Florida had failed to meet the “exacting standard” of proving its case by “clear and convincing evidence.” The evidence showed the oyster collapse could have been caused by other factors, including severe drought itself and Florida’s own mismanagement of the fishery, such as allowing record oyster harvests in years leading up to the collapse.

The case serves as a stark reminder that in disputes between co-equal sovereigns, the Court won’t reallocate vital resources without overwhelming proof of causation.

Kansas v. Nebraska: Enforcing Existing Agreements

Sometimes disputes aren’t about initial water division but enforcing pre-existing agreements. In Kansas v. Nebraska (2015), the issue was Nebraska’s violation of the 1943 Republican River Compact. Kansas alleged that Nebraska’s massive increase in groundwater pumping was depleting the river’s flow, thereby taking more than its allocated share under the compact.

The Special Master found that Nebraska had “knowingly failed” to comply with its obligations, essentially gambling with Kansas’s water rights. The Supreme Court adopted the Master’s findings and deployed powerful remedies. It ordered Nebraska to pay Kansas $3.7 million in damages for its losses.

More significantly, it also ordered Nebraska to pay an additional $1.8 million in “disgorgement” of profits it had unfairly gained by using Kansas’s water. This remedy was designed not just to compensate Kansas but to deter Nebraska and other states from violating compacts in the future, demonstrating that a state can’t simply take another’s resources and treat resulting damages as mere cost of doing business.

When Pollution Crosses Borders

In the latter half of the 20th century, a new kind of interstate conflict emerged, driven by industrialization consequences: pollution drifting across state lines. While a state could theoretically bring an original jurisdiction case against a neighboring state for polluting its air or water, this has become exceedingly rare.

The reason is that Congress created a different legal framework for handling these problems. The passage of comprehensive federal environmental laws, most notably the Clean Air Act (CAA) and Clean Water Act (CWA), established a national regulatory system administered by the Environmental Protection Agency (EPA).

These laws created new, more direct avenues for states to address cross-border pollution. Under the CAA’s “Good Neighbor” provision, states are legally required to ensure their own pollution sources don’t prevent downwind states from meeting federal air quality standards for pollutants like ozone.

If an upwind state fails to submit an adequate plan to control its pollution, the CAA requires EPA to step in and create a Federal Implementation Plan (FIP) that imposes necessary emissions cuts.

The Shift in Environmental Battles

The modern environmental battlefield has shifted. Instead of New York suing Pennsylvania directly in the Supreme Court over smog, New York and a coalition of other downwind states will typically sue EPA in a federal court of appeals. The goal of such lawsuits is compelling EPA to fulfill its statutory duty to enforce the “Good Neighbor” provision against upwind states.

The legal fight becomes a challenge to federal regulatory action—or inaction—rather than direct confrontation between states in the Supreme Court’s original docket. This demonstrates how Congress can create alternative legal pathways that effectively channel and resolve interstate conflicts without relying on the Court’s extraordinary original jurisdiction.

The New Frontier: Interstate Policy Battles

In the 21st century, a new type of interstate conflict has emerged, reflecting the nation’s deep political polarization. States have increasingly formed partisan coalitions to wage legal battles over major national policies’ validity. The Supreme Court’s original jurisdiction has been seen as a potential venue for these fights, but the Court has proven to be a reluctant referee.

The landmark case California v. Texas (2021) exemplifies this trend. The case was the third major Supreme Court challenge to the Affordable Care Act (ACA). The lawsuit was initiated by a coalition of 18 Republican-led states, with Texas at the forefront, arguing that the entire ACA should be struck down as unconstitutional.

The law was defended by a coalition of Democratic-led states, led by California, as well as the U.S. House of Representatives.

A Novel Legal Argument

The plaintiffs’ legal argument was novel. They pointed to the fact that in 2017, Congress had reduced the tax penalty for the ACA’s individual mandate—the requirement to have health insurance—to zero. They argued that since the Supreme Court had previously upheld the mandate only under Congress’s taxing power, a mandate with a $0 penalty was no longer a tax but an unconstitutional command to buy a product.

They further argued that the mandate was essential to the entire law and couldn’t be “severed,” meaning the whole ACA had to fall with it.

Standing as a Gatekeeper

The Supreme Court never addressed the merits of this constitutional claim. In a 7-2 decision, the Court dismissed the case on procedural grounds, ruling that plaintiffs lacked legal standing to bring the lawsuit in the first place.

The doctrine of standing is a core constitutional requirement that a plaintiff must demonstrate they have suffered a concrete, traceable injury that a court can remedy. The Court reasoned that since the individual mandate’s penalty was now $0, it was completely unenforceable. An unenforceable law, the majority concluded, couldn’t possibly injure anyone. Without demonstrable injury, there was no “case or controversy” for a federal court to decide.

This ruling powerfully illustrates the Supreme Court’s role as gatekeeper. By strictly applying procedural doctrines like standing, the Court polices the boundary between genuine legal disputes and purely political disagreements.

The decision in California v. Texas sent a clear signal: the courthouse isn’t the appropriate venue for refighting legislative battles. If a state disagrees with a federal law, its remedy lies in the political process—through Congress or elections—not through lawsuits lacking concrete legal injury.

This gatekeeping function is critical to preserving the Court’s legitimacy and its intended role as a judicial body, not a third political branch. It ensures that extraordinary power to resolve disputes between states is reserved for actual conflicts over tangible rights and resources, not abstract disagreements over national policy.

A Lasting Framework

The system the Framers created in Article III has evolved far beyond their original vision but remains true to its core purpose: providing a peaceful, authoritative mechanism for resolving conflicts between states that might otherwise tear the nation apart.

From boundary disputes over Ellis Island to water wars in the West to modern policy battles, the Supreme Court’s original jurisdiction has adapted to meet each era’s challenges. The Court has shown remarkable wisdom in exercising this power sparingly, using procedural doctrines to screen out political disputes while maintaining its role as ultimate arbiter of genuine interstate conflicts.

The Special Master system demonstrates American institutional ingenuity—a way to preserve the Supreme Court’s appellate character while fulfilling its constitutional duty as trial court for the states. This hybrid approach has allowed the Court to handle complex, evidence-heavy disputes without compromising its primary mission.

As the nation continues to evolve and new forms of interstate conflict emerge, the framework established in 1787 and refined through more than two centuries of practice provides a durable foundation for maintaining the peace among fifty sovereign states within one federal system. The alternative—a return to the chaos of the 1780s—remains as unappealing today as it was to the Framers who sought to form a more perfect Union.

Our articles make government information more accessible. Please consult a qualified professional for financial, legal, or health advice specific to your circumstances.