Concurrent jurisdiction is the shared authority of federal and state courts to hear the same case. When a dispute qualifies for both systems, the plaintiff picks where to file, and the defendant may be able to move the case to the other court. Most civil lawsuits in the United States live inside this shared space, which is why the choice of courtroom often shapes strategy as much as the underlying law does.
The Two Paths That Create Shared Authority
Federal courts are courts of limited power. They can only hear cases Congress has specifically authorized them to hear. Two statutes do most of the work, and both create overlap with state courts rather than displacing them.
The first is federal question jurisdiction. Under 28 U.S.C. § 1331, federal district courts can hear any case “arising under the Constitution, laws, or treaties of the United States.”1Office of the Law Revision Counsel. 28 USC 1331 – Federal Question A claim built on a federal statute, a constitutional right, or a treaty qualifies. A federal civil rights discrimination claim, for example, can be filed in either federal or state court. Both systems have the power to resolve it.
The second is diversity of citizenship. Under 28 U.S.C. § 1332, federal courts can hear cases between citizens of different states when the amount in dispute exceeds $75,000, exclusive of interest and costs. The diversity must be complete: every plaintiff must be from a different state than every defendant. For corporations, citizenship covers both the state of incorporation and the state of the principal place of business.2Office of the Law Revision Counsel. 28 USC 1332 – Diversity of Citizenship; Amount in Controversy; Costs A company incorporated in Delaware with headquarters in New York is a citizen of both states for jurisdictional purposes.
State courts carry inherent general jurisdiction. They can hear almost any civil or criminal matter, regardless of federal thresholds. So when a case meets § 1331 or § 1332, the state court does not lose its authority. The two systems hold it together.
When Jurisdiction Is Exclusive to Federal Court
Shared authority is the default, but not the whole picture. Congress has reserved certain subjects for federal court alone, and filing those claims in state court is a dead end.
Bankruptcy is the clearest example. Federal district courts have “original and exclusive jurisdiction of all cases under title 11.”3Office of the Law Revision Counsel. 28 USC 1334 – Bankruptcy Cases and Proceedings You cannot file for bankruptcy in state court.
Patent, plant variety protection, and copyright cases are also federal-only. The governing statute states that “no State court shall have jurisdiction over any claim for relief arising under any Act of Congress relating to patents, plant variety protection, or copyrights.”4GovInfo. 28 USC 1338 – Patents, Plant Variety Protection, Copyrights, Mask Works, Designs, Trademarks, and Unfair Competition
Admiralty and maritime cases follow the same pattern. Federal district courts have original jurisdiction “exclusive of the courts of the States” over civil admiralty matters and prize cases, though the statute preserves certain alternative remedies for litigants.5Office of the Law Revision Counsel. 28 USC 1333 – Admiralty, Maritime, and Prize Cases
These exclusive categories are exceptions. The ordinary case that reaches federal court also fits inside state court authority, which is why most litigants are operating in the concurrent space.
Why the Choice of Court Matters
When a case qualifies for both systems, the plaintiff files first and the forum choice is theirs. The two courts differ in ways that can affect the outcome.
Procedure is the biggest divide. Federal courts apply the Federal Rules of Civil Procedure and the Federal Rules of Evidence, which are uniform across every district. State courts follow their own rules, which vary from state to state and sometimes from county to county. Those differences touch discovery, motions practice, and what expert testimony makes it in front of a jury.
Juries are drawn from different pools. State juries typically come from a single county, while federal juries are drawn from an entire judicial district that may cover many counties or most of a state.6United States Courts. Juror Selection Process The wider federal pool tends to produce a more demographically mixed panel, which some attorneys read as favorable depending on the case.
Cost plays a smaller role but is worth knowing. The federal district court filing fee is $350 for most civil cases.7Office of the Law Revision Counsel. 28 USC 1914 – District Court Filing Fees State filing fees vary widely by jurisdiction and case type, generally ranging from under $100 to several hundred dollars.
How Removal Lets a Defendant Change Courts
The plaintiff picks the initial forum. The defendant gets a response. If the case qualifies for federal jurisdiction, the defendant can move it from state court to federal court through removal.
The defendant files a notice of removal in the federal district court covering the location of the state court. The notice includes a short statement of the basis for federal jurisdiction, whether federal question or diversity, along with copies of everything served on the defendant in the state case: the summons, the complaint, and any motions or orders. The original state case number and the names of every party must also appear.8Office of the Law Revision Counsel. 28 USC Chapter 89 – District Courts; Removal of Cases from State Courts – Section 1446
After filing in federal court, the defendant must promptly give written notice to all opposing parties and file a copy of the notice with the state court clerk. Once the state court clerk receives it, the state court must stop all proceedings. The case now sits in the federal system unless a court sends it back.8Office of the Law Revision Counsel. 28 USC Chapter 89 – District Courts; Removal of Cases from State Courts – Section 1446
The Forum Defendant Rule
Diversity-based removal has a restriction that catches defendants off guard. A case otherwise removable on diversity grounds cannot be removed if any properly joined and served defendant is a citizen of the state where the lawsuit was filed.9Office of the Law Revision Counsel. 28 USC 1441 – Removal of Civil Actions Diversity jurisdiction exists to protect out-of-state defendants from potential home-court bias. A defendant already in its home state’s court does not need that protection.
The Unanimity Requirement
Where multiple defendants are involved, every properly joined and served defendant must consent to removal.10Office of the Law Revision Counsel. 28 USC 1446 – Procedure for Removal of Civil Actions A single defendant cannot pull the case into federal court over the objections of co-defendants. Removal often fails here, because coordinating consent on a short deadline is harder than it sounds.
Removal Deadlines
Missing a removal deadline permanently waives the right to move the case. The timing is strict.
The baseline is 30 days. A defendant must file the notice of removal within 30 days of receiving the initial complaint or summons, whichever comes first. If the case was not removable when first filed but later becomes removable, such as when a non-diverse defendant drops out, a new 30-day window opens from the date the defendant learns the case has become removable.8Office of the Law Revision Counsel. 28 USC Chapter 89 – District Courts; Removal of Cases from State Courts – Section 1446
Diversity cases carry a hard outer limit. They cannot be removed on diversity grounds more than one year after the original filing, even if diversity only becomes apparent later. The one exception is bad faith. If the court finds the plaintiff deliberately structured the case to prevent removal, such as by hiding the true amount in controversy, removal can proceed past the one-year mark.10Office of the Law Revision Counsel. 28 USC 1446 – Procedure for Removal of Civil Actions
Sending a Case Back Through Remand
If a case was improperly removed, the plaintiff can fight to send it back to state court through a motion for remand under 28 U.S.C. § 1447. The timing depends on the problem.
For procedural defects in the removal itself, such as a missed deadline or missing defendant consent, the plaintiff has to file the remand motion within 30 days of the removal notice.11Office of the Law Revision Counsel. 28 USC 1447 – Procedure After Removal Generally After that, the procedural defect is waived.
For lack of subject matter jurisdiction, the rules are more forgiving. If the federal court never had proper jurisdiction, the case must be sent back any time before final judgment, with no deadline for the plaintiff to raise the issue.11Office of the Law Revision Counsel. 28 USC 1447 – Procedure After Removal Generally Federal judges can and must raise this on their own. A judge who realizes mid-case that diversity was never complete, or that the amount in controversy falls short, must remand regardless of whether anyone asked.
A remand order returns the case to the state court where it started, and proceedings resume there. The remand order itself usually cannot be appealed, which puts a premium on getting the removal right the first time.
What Law Applies Once a Case Is in Federal Court
A question that trips up litigants: if a state-law claim ends up in federal court through diversity jurisdiction, does the federal court apply federal law or state law? Under the Erie doctrine, the answer is both, depending on the issue.
The rule comes from the Supreme Court’s 1938 decision in Erie Railroad Co. v. Tompkins. Federal courts hearing diversity cases apply state substantive law but follow federal procedural rules. Substantive law covers the legal rights and obligations at stake, such as the elements of a negligence claim or the measure of damages. Procedural law covers how the case moves through court, including filing deadlines and discovery rules under the Federal Rules of Civil Procedure.
The line sounds clean and gets messy in practice. Under the Supreme Court’s 1945 decision in Guaranty Trust Co. v. York, if ignoring a state rule would significantly change the result of the litigation, that rule is substantive and the federal court must follow it. Later decisions refined the test by asking whether applying a federal rule instead of a state rule would encourage parties to forum-shop, picking federal court specifically to dodge less favorable state rules.
The underlying concern is fairness. A plaintiff should not get a different result just because the case landed in federal court instead of state court. Concurrent jurisdiction gives litigants a choice of courtroom. The Erie doctrine makes sure that choice does not quietly change the law that decides who wins.