By Mike Colias

A federal judge dismissed a General Motors Co. lawsuit accusing Fiat Chrysler Automobiles NV of bribing union officials to gain an advantage on its labor costs, dealing a blow to GM in an unusual legal standoff between rival automotive giants.

GM in November filed a civil racketeering lawsuit against Fiat Chrysler, claiming the Italian-American auto maker intentionally hurt GM by paying off United Auto Workers leaders to win more-favorable contract terms for union-represented factory workers.

On Wednesday, U.S. District Judge Paul Borman said GM failed to show it was the primary victim of any alleged racketeering activity that Fiat Chrysler officials may have engaged in.

A GM spokesman didn't immediately reply to a request for comment.

Write to Mike Colias at Mike.Colias@wsj.com