Civil Procedure In Interstate Disputes
Legal disputes between U.S. states (or between the United States government and a U.S. state, or both) are resolved in the U.S. Supreme Court and in these disputes, the U.S. Supreme Court has original jurisdiction.* This means that the U.S. Supreme Court functions as a trial court, rather than as an appellate court in these cases.
- The original jurisdiction of the United States also includes cases involving ambassadors and suits by a U.S. state against someone who is not a citizen of that state. So, for example, if there was a question over the correct boundaries of the property upon which the French embassy is located, between it and a neighboring property owner, that would be decided in the U.S. Supreme Court in the first instance.
In practice, the U.S. Supreme Court appoints a "special master" (i.e. a magistrate appointed on an ad hoc basis in that particular case only) to take evidence and receive legal arguments from the parties who then provides a summary of the facts and the relevant law to the U.S. Supreme Court justices which they use as a foundation render their opinion.
Apart from the unusual forum of the litigation, the relevant law is basically the same as any other private civil litigation, although these suits tend to involve only moderate amounts of discovery and many key facts are routinely stipulated by the parties as represented by their state solicitor generals (the solicitor general is the lawyer within a U.S. attorney general's office or state attorney general's office in charge of state supreme court and U.S. Supreme Court litigation). But, nonetheless, these cases routinely go on for many years.
Generally speaking, once the U.S. Supreme Court issues an order in an original jurisdiction case involving U.S. states, the U.S. state parties then comply voluntarily with the order, so it isn't necessary to have federal marshals or the U.S. military, for example, insure that the orders are carried out.
Disputes involving local governments are usually handled in federal trial courts unless a state in which the local government is not located is a party and does not consent to another forum.
U.S. states routinely waive their right to a U.S. Supreme Court or state court forum and instead consent to the jurisdiction of the U.S. Bankruptcy Court in cases where the U.S. state is just one of many parties with a claim in a bankruptcy estate, for example, for unpaid taxes or fines or contract debts owed to the state. For example, when General Motors went bankrupt, multiple U.S. states were owed money for unpaid taxes by this large interstate corporation, but all of the states owed money chose to participate in the U.S. Bankruptcy Court process by consent, rather than litigating their indirect dispute with other states over their share of the available assets in the bankruptcy in the U.S. Supreme Court, even though they had a right to do so.
Substantive Law In Interstate Disputes
In practice, most of the one to two cases a year on average filed in the original jurisdiction of the U.S. Supreme Court between U.S. states (on average about one of the two to three original jurisdiction cases a year involve disputes other than water rights or boundary disputes between states) involve water rights in the arid west of the United States, and these water rights are governed by interstate compacts, which are like treaties entered into between U.S. states except that they must be approved by Congress to be valid, or boundary disputes. From the link above:
On average, only two to three of the nearly 100 cases heard annually
by the Supreme Court are considered under original jurisdiction.
However, many are still important cases.
Most original jurisdiction cases involve border or water rights
disputes between two or more states, meaning they can only be resolved
by the Supreme Court. For example, the now famous original
jurisdiction case of Kansas v. Nebraska and Colorado involving the
rights of the three states to use the waters of the Republican River
was first placed on the Court’s docket in 1998 and was not decided
until 2015.
These interstate compacts have detailed provisions governing how U.S. states that are parties to the contract must manage their water resources to insure that a sufficient flow of water makes its way from upstream states to downstream states and then further (in some cases) to Mexico with whom the United States has a similar treaty governing water rights.
For example, the interstate compacts prohibit upstream states from diverting too much water via groundwater wells from interstate rivers that are subject to the compact, thereby reducing the amount of water that downstream states receive.
A suit on that ground involving Texas and New Mexico and Colorado and the United States Government, over water rights in the Rio Grande River, is pending right now.
An interesting non-water rights case between U.S. states that recently came before the U.S. Supreme Court and was ultimately dismissed, involved a claim of nuisance filed by the States of Nebraska and Oklahoma against the State of Colorado, alleging that Colorado's state regulated marijuana industry caused a nuisance that affected Nebraska by providing a source for illegal interstate marijuana shipments to Nebraska which burdened state law enforcement resources.
The Question
So if a state tries to build a dam to block water to flow in the other
state or uses some other drastic measure then can the federal
government force one state to share it's water (or other) resources
with the neighbouring states, because it's part of the same nation?? What > are the legal implications? Would U.S. supreme court has to intervene to > stop such events?
Yes. The aggrieved state could demand that the other state not block its flow of water and could enforce its rights in a lawsuit filed in the U.S. Supreme Court.
Also, the fact that the U.S. Supreme Court can and will intervene in situations like these creates a strong incentive for U.S. states not to violate their legal obligations to neighboring states. The vast majority of the time, when happens in a situation like this is that the state attorney general or governor of the aggrieved state writes a letter to and/or meets with a counterpart holding the same office in the state engaged in the misconduct in person or by telephone and raises the concern and the dispute is worked out via direct negotiations between the parties. Just as 95% of lawsuits between private parties are resolved by settlement, the vast majority of disputes between U.S. states are resolved by settlement, although in disputes between U.S. states, those settlements are far more often reached before, rather than after, a lawsuit is filed.
But, while the legal basis of the ruling in the interstate water dispute could be the fact that it is part of the same nation, and that was the legal basis of some rulings in the early days of the United States, these days the ruling would usually be based upon an alleged violation of an interstate compact to which all states involved and the U.S. Congress had agreed setting out the right and obligations of the respective states in detail. So, it is no longer necessary to resort to court made common law precedents to resolve most interstate disputes (although boundary disputes between U.S. states often do involve the common law of property rights).
Also "force" is a bit of a dramatic choice of words for how the right is enforced.
I'm not aware of any instance in U.S. history when a state government defied a federal court order in a case to which it was a party to take action once a judgment was entered in that case. (The famous Little Rock desegregation case in the 1950s in which the National Guard was sent in to enforce a federal court order involved defiance by a local government rather than a U.S. state.)
Commentary
It is somewhat remarkable how well the system of resolving disputes between U.S. states within a single country through the courts works compared to the dealings between comparable sovereign nations that have similarly strong economic ties to each other (with the obvious exception of the U.S. Civil War, which nonetheless probably would have happened much sooner but for the role of courts and federal institutions in resolving disputes between slave and non-slave states in the decades leading up to it).
Part of why this works as well as it does is that the appellate role of the U.S. Supreme Court over state court actions, the role of the federal trial courts in sanctioning violations of federal rights by local governments and state officials, and the incentives created by federal statutes for state governments to submit to myriad programs coordinated between the federal government and state governments, means that state governments aren't nearly as autonomous and independent from each other and from the federal government as a naive cold reading of the U.S. Constitution would suggest.
U.S. states are in the habit of conforming to federal law in comparatively minor matters, like how they handle serious criminal trials or how police exercise their discretion in traffic stops, so the legitimacy of the federal government and the U.S. Supreme Court, in particular, to intervene authoritatively and decisively in their internal affairs is fully acknowledged.