as well, but our determination that WMATA is immune from liability to Watters moots the Authority’s third-party claim. 2 . WMATA did not raise this defense in its answer to Watters' complaint, but did raise it both in subsequent filings in the district court and in its opening brief in this court. Sovereign immunity is a jurisdictional issue that may be raised at any time during the course of litigation. Burkhart v. Washington Metro. Area Transit Auth., 112 F.3d 1207, 1216 (D.C.Cir.1997). 3 . On November 6, 1966, Congress consented to the WMATA Compact and enacted it for the District mbia, 704 A.2d 288, 290 (D.C.1997) (garnishment); Chewning v. District of Columbia, 119 F.2d 459, 460 (D.C.Cir.1941) (garnishment); Mayor of Baltimore v. Hooper, 312 Md. 378, 539 A.2d 1130, 1132 (1988) (<HOLDING>); Kator, Scott, & Heller, PC v. Landsidle, 35
holding that the defense of sovereign immunity is not available in the absence of a statute providing immunity to a municipal corporation in a negligence action holding upon considerations of public policy rather than sovereign immunity that municipal corporations are not amenable to garnishment holding that city could not appeal based on sovereign rather than official immunity under section 510145 holding that the public policy considerations supporting public officials immunity required that the immunity be applied to bar contribution actions as well as direct actions holding that in the absence of a statute providing immunity the defense of sovereign immunity is not available to a municipal corporation in an action for damages alleged to be caused by the tortious conduct of the municipality