Does a district court's pretrial order denying a government contractor protection under *Yearsley v. W. A. Ross Constr. Co.* qualify for immediate interlocutory appeal? Specifically, the Court must determine if such a denial satisfies the collateral-order doctrine's requirements for review before a final judgment. The central issue is whether *Yearsley* provides a merits defense to liability or an immunity from suit.

• Sought the reversal of the Tenth Circuit's dismissal to allow an immediate appeal of the denial of *Yearsley* protection.
• Argued that *Yearsley* provides "derivative sovereign immunity," whereby the Government's own immunity extends to contractors who meet specified conditions.
• Contended that this immunity grants the "right not to stand trial," making a pretrial denial irretrievably lost if the case proceeds to trial.
• Asserted that the order satisfies the three conditions for interlocutory review distilled from *Cohen v. Beneficial Industrial Loan Corp.*

• Sought the affirmation of the Tenth Circuit's dismissal of the appeal.
• Argued that *Yearsley* provides a merits defense rather than an immunity, as it only protects contractors who can show their conduct complied with the law.
• Contended that a denial of a merits defense is not immediately appealable because the right to a finding of non-liability can be effectively vindicated after a final judgment.
• Asserted that the order fails the third condition of the *Cohen* test because it is not "effectively unreviewable" on appeal.

• The Court held that a pretrial order denying *Yearsley* protection is not immediately appealable under 28 U. S. C. § 1291.
• The Court applied the "final-judgment rule," which generally limits appellate jurisdiction to "final decisions of the district courts" to prevent piecemeal appeals and promote the "efficient administration of justice" (*Ritzen Group, Inc. v. Jackson Masonry, LLC*; *Microsoft Corp. v. Baker*).
• The Court analyzed the "collateral-order doctrine" from *Cohen v. Beneficial Industrial Loan Corp.*, which requires that a prejudgment order (1) conclusively determine the disputed question, (2) resolve an important issue completely separate from the merits, and (3) be "effectively unreviewable on appeal from a final judgment" (*Van Cauwenberghe v. Biard*).
• The Court distinguished between an "immunity from suit," which is in its "essence" an "entitlement not to stand trial" (*Mitchell v. Forsyth*), and a "merits defense," which is a right to a finding of non-liability.
• The Court determined that *Yearsley v. W. A. Ross Constr. Co.* provides a merits defense because its protection only applies when a contractor's work was lawfully "authorized and directed" by the Government and the contractor stayed within the bounds of that authority.
• The Court reasoned that *Yearsley* cannot be an immunity because it "will never shield unlawful conduct," whereas immunities apply regardless of whether the defendant acted wrongly (*Richardson v. McKnight*).
• The Court rejected the notion of "derivative sovereign immunity," citing *Sloan Shipyards Corp. v. United States Shipping Bd. Emergency Fleet Corporation*, *Keifer & Keifer v. Reconstruction Finance Corporation*, and *Brady v. Roosevelt S. S. Co.* to establish that sovereign immunity is not transferable to government agents or contractors.
• Because *Yearsley* is a merits defense, the right it protects—non-liability—is not "irretrievably lost" at trial and can be vindicated through the reversal of an adverse final judgment, thus failing the third *Cohen* condition.