46 U.S.C. § 31102
Waiver of immunity
(a) In General.—
A civil action in personam in admiralty may be brought, or an impleader filed, against the United States for—
(1)
damages caused by a public vessel of the United States; or
(2)
compensation for towage and salvage services, including contract salvage, rendered to a public vessel of the United States.
(b) Counterclaim or Setoff.—
If the United States brings a civil action in admiralty for damages caused by a privately owned vessel, the owner of the vessel, or the successor in interest, may file a counterclaim in personam, or claim a setoff, against the United States for damages arising out of the same subject matter.
( Pub. L. 109–304, § 6(c) , Oct. 6, 2006 , 120 Stat. 1521 .)