The multi-billion dollar settlement that was reached last month between Visa/MasterCard and a number of U.S. merchants to end years of litigation is already in the appeal process. 

According to an article from Business Insider, American Express has filed in federal court in Brooklyn, New York to join several trade associations including Wal-Mart, Amazon, 7-Eleven and Barnes and Noble that have already filed an appeal of the decision.

This all stems from the decision on December 13 by U.S. District Judge John Gleeson. He approved a $5.7 billion settlement that ends eight years of litigation from a lawsuit against credit companies Visa and MasterCard. The allegations are that the card companies were charging unlawful excessive swipe and processing fees.

Despite receiving money from the settlement, there were a number of organizations that came out against the ruling. The National Retail Federation expressed disappointment and frustration with the decision, stating it forces merchants to accept a settlement they do not agree with and will ultimately do little to protect their rights and their customers' finances. There is also a belief that the settlement is too low.

"The language of the release that Visa and MasterCard required in their settlement is so broad that defendants in that case could argue that it applies to claims of competitors, not just merchants," Marina Norville, vice president of public affairs and communications at AmEx, told the news source.

Despite nearly a decade of debate, it seems as though this issue of merchant interchange rate and service fees continues to rage and could for some time.