A state appeals court dismissed Dan Rather's lawsuit against his former bosses at CBS Corp. (CBS) on Tuesday, dealing a possible knockout blow to the news anchor's high-profile dispute over the circumstances of his departure from the network.

Rather, 77, alleged that CBS ruined his reputation, making him a scapegoat for a flawed 2004 story on then-President Bush's Vietnam-era Texas Air National Guard service. The story aired during that year's presidential election.

In an unanimous decision, the appellate court ruled that Rather's claim "must be dismissed in its entirety."

The New York court said Rather's claim that his career was damaged because of fraud and breach of contract by CBS was "unavailing," noting the newsman admits the network was already contemplating he would step down to a reduced role in 2006.

"As to lost opportunities in the trade," the court ruled that Rather "never identified a single opportunity with specified terms that was actually available to him and which he declined to accept because of CBS' actions."

CBS spokesman Jeff Ballabon said, "This lawsuit is now effectively over" and it was a "total victory - and vindication for CBS' position."

Rather's lead attorney, Martin Gold, said in a statement that "we are extremely disappointed" with the court's decision. He added that "the decision is incorrect on a number of grounds and, accordingly, we intend to ask the New York Court of Appeals to review it."

Rather, who joined CBS News in 1962, has also claimed CBS conducted a biased investigation instead of the independent probe it promised into the underlying story and its production.

Rather left the network in June 2006, after CBS was spun off by Viacom (VIA). He now works for HDNet.

-By Nat Worden, Dow Jones Newswires; 212-416-2472; nat.worden@dowjones.com