But the judge has permitted Mr. Rather to go forward with the core of his case, including his argument that CBS had limited his work as a correspondent after he left the anchor desk and, in the process, damaged his reputation. The case is on track to go to trial soon, possibly early in the new year.

Those who have worked on the case with Mr. Rather, 77, say he has approached it with the zeal of a correspondent trying to report out a “60 Minutes” segment about himself, burying himself in deposition transcripts late into the night and providing his lawyers with road maps of leads he thinks they should pursue. He rarely misses a court hearing on the case.

“I want to go the distance,” Mr. Rather said recently over a lunch of chili and cornbread at a barbecue restaurant. “Like any good reporter, I want to get as many as facts as possible; I want to get to the bottom of the story.”

Some of the documents unearthed by his investigation include notes taken at the time by Linda Mason, a vice president of CBS News. According to her notes, one potential panel member, Warren Rudman, a former Republican senator from New Hampshire, was deemed a less-than-ideal candidate over fears by some that he would not “mollify the right.”

Meanwhile, Mr. Thornburgh, who served as attorney general for both Ronald Reagan and George H. W. Bush, was named a panelist by CBS, but only after a CBS lobbyist “did some other testing,” in which she was told, according to Ms. Mason’s notes, “T comes back with high marks from G.O.P.”

Another memorandum turned over to Mr. Rather’s lawyers by CBS was a long typed list of conservative commentators apparently receiving some preliminary consideration as panel members, including Rush Limbaugh, Matt Drudge, Ann Coulter and Pat Buchanan. At the bottom of that list, someone had scribbled “Roger Ailes,” the founder of Fox News.

Asked about the assembly of the panel in a sworn deposition, Andrew Heyward, the former president of CBS News, acknowledged that he had wanted at least one member to sit well with conservatives: “CBS News, fairly or unfairly, had a reputation for liberal bias,” and “the harshest scrutiny was obviously going to come from the right.”