Federal Jurisdiction
The American legal system includes both state courts and federal courts. Generally, state courts hear cases involving state law, although they may also hear cases involving federal law so long as the federal law in question does not grant exclusive jurisdiction to federal courts. Federal courts may only hear cases where federal jurisdiction can be established. Specifically, the court must have both subject-matter jurisdiction over the matter of the claim and personal jurisdiction over the parties . The Federal Courts are courts of limited jurisdiction, meaning that they can only exercise the powers that are granted to them by the Constitution and federal laws. For subject matter jurisdiction, the claims in the case must either: raise a federal question, such as a cause of action or defense arising under the Constitution; a federal statute, or the law of admiralty; or have diversity of parties. For example, all of the defendants are from a different state than the plaintiff, and have an amount in controversy that exceeds a monetary threshold (which changes from time to time, but is $75,000 as of 2011).
Federal district courts
The federal district courts represent one of the ways federal jurisdiction is split.
If a Federal Court has subject matter jurisdiction over one or more of the claims in a case, it has discretion to exercise ancillary jurisdiction over other state law claims.
The Supreme Court has "cautioned that ... Court[s] must take great care to 'resist the temptation' to express preferences about [certain types of cases] in the form of jurisdictional rules. Judges must strain to remove the influence of the merits from their jurisdictional rules. The law of jurisdiction must remain apart from the world upon which it operates."
Generally, when a case has successfully overcome the hurdles of standing, Case or Controversy, and State Action, it will be heard by a trial court. The non-governmental party may raise claims or defenses relating to alleged constitutional violation(s) by the government. If the non-governmental party loses, the constitutional issue may form part of the appeal. Eventually, a petition for certiorari may be sent to the Supreme Court. If the Supreme Court grants certiorari and accepts the case, it will receive written briefs from each side (and any amicae curi or friends of the court—usually interested third parties with some expertise to bear on the subject) and schedule oral arguments. The Justices will closely question both parties. When the Court renders its decision, it will generally do so in a single majority opinion and one or more dissenting opinions. Each opinion sets forth the facts, prior decisions, and legal reasoning behind the position taken. The majority opinion constitutes binding precedent on all lower courts; when faced with very similar facts, they are bound to apply the same reasoning or face reversal of their decision by a higher court.