A federal judge has dismissed a long-running class action lawsuit over airline baggage fees.

In the lawsuit that dates back to 2009, attorneys for consumers argued that Delta Air Lines and AirTran Airways had colluded to charge baggage fees back in 2008. In 2015, Delta was slapped with million in sanctions in the case for failing to turn over evidence.

However, U.S. District Judge Timothy Batten in Atlanta determined that “the evidence in this case simply does not permit a reasonable factfinder to infer the existence of a conspiracy,” according to a decision granting summary judgment to Delta and AirTran this week.

AirTran was swallowed up by Southwest Airlines in an acquisition in 2011.

But back in 2008, AirTran was looking for ways to generate more revenue, and some airlines had begun charging fees for checked bags.

AirTran’s CEO in an earnings call on Oct. 23, 2008 indicated that AirTran decided not to charge baggage fees, “primarily because our largest competitor in Atlanta where we have 60 percent of our flights hasn’t done it.... I think we prefer to be a follower in a situation rather than a leader.”

On Nov. 5, 2008, Delta announced it would charge fees for the first and second checked bags. AirTran followed the move on Nov. 12.

But the judge’s ruling said there were also “valid reasons to impose a first-bag fee,” including the airlines’ “need for revenue during an economic downturn.”

The order also refers to “conscious parallelism,” described as “synchronous pricing and related behaviors that ‘are the product of a rational, independent calculus by each member of an oligopoly’” -- a phenomenon such as price matching among airlines and in other industries.

“But it is often difficult to discern when lawful coordination crosses the line and becomes unlawful collusion,” the order says.

Delta declined to comment on the case.

Daniel Low, an attorney for the plaintiffs in the case, issued a statement saying: “We disagree with the court’s ruling and are disappointed that the court would deny consumers the opportunity to present their claims to a jury,” adding that “we are very hopeful that the ruling will be overturned on appeal.”