Baggage fee lawsuit now includes millions of fliers

That group that potentially consists of more than 28 million people, according to the judge’s order.

An appeal of the ruling is expected. Delta declined to comment.

The lawsuit seeks damages totaling all fees for passengers' first checked bags paid during the period, with amounts tripled under anti-trust law. However, payouts to consumers in class action lawsuits are often minimal.

Batten’s order this week is the latest development in a lawsuit that dates to 2009.

The lawsuit filed that year claimed AirTran invited Delta to collude on charging a first checked bag fee by signaling that it wanted to charge the fee if Delta acted first -- and that Delta accepted the invitation by announcing its fee shortly afterward.

A key example of the signaling, the plaintiffs allege, came during a conference call with analysts on the company’s financial results. In 2008, then-AirTran CEO Bob Fornaro said during the call that AirTran had not started charging a first-bag fee "primarily because our largest competitor in Atlanta" had not done it.

Delta announced its checked bag fee for passengers' first piece of luggage on any flight a couple of weeks after the conference call, and AirTran followed. Southwest Airlines, which does not charge for checked bags, has since acquired AirTran. Delta still charges the fees, which have become common among most carriers.

The judge’s decision Tuesday could move the case forward as a massive class action lawsuit.

The plaintiffs in the case "are pleased to have the opportunity to seek to vindicate the rights of the millions of passengers who we believe were overcharged by Delta or AirTran for first bag fees," according to Daniel Low, an attorney representing airline passengers who are plaintiffs in the case.