Chatham County, Georgia owned, operated, and maintained the Causton Bluff Bridge, a drawbridge over the Wilmington River.

[2] The District Court granted the County's motion for summary judgment on the ground that the suit was barred by sovereign immunity.

However, the court nonetheless concluded that a "residual immunity" had been carved out by American common law that protected political subdivisions such as Chatham County.

The Supreme Court granted certiorari to consider "whether an entity that does not qualify as an 'arm of the State' for Eleventh Amendment purposes can nonetheless assert sovereign immunity as a defense to an admiralty suit.

The Court ruled that the county was not entitled to immunity from Northern's suit because it had failed to demonstrate that it was acting as an "arm of the state" when it operated the bridge.

The Court had repeatedly refused to extend sovereign immunity to municipalities (of which counties are a class), even when they exercised delegated state power.