"The reasonable, objective analysis is it was a bad day at Black Rock," Rather, 77, said about CBS's midtown Manhattan headquarters.
The anchorman sued his former employer two years ago after he claimed CBS used him as a scapegoat for the controversy that erupted over the reporting of President George W. Bush's service in the National Guard during the Vietnam War.
New York State Supreme Court Judge Ira Gamerman, who had previously thrown out the fraud claim, ruled that Rather could file an amended complaint.
The judge also granted Rather access to thousands of documents his attorneys believe will help show the anchorman was unfairly blamed for the incident, in which documents later suspected to be fakes were used to show Bush dodged active duty in Vietnam.
Rather left the network in June 2006 and said CBS violated his contract by not giving him the designated number of on-air assignments on "60 Minutes" or "60 Mintues II." He has since resurfaced on cable station HDNet, where he hosts a weekly one-hour show called "Dan Rather Reports."
CBS said it was going to appeal the ruling.
"Today's rulings by Judge Gammerman were on technical and procedural issues, not on the merits of Mr. Rather's allegations," the network said in a statement.
"Most of Mr. Rather's claims already have been rejected by the court and that has not changed. We are similarly confident that Mr. Rather's re-pleaded fraud claim will be dismissed once the court reaches the actual merits."