A long-standing dispute between credit card issuers Visa (NYSE:V) and MasterCard (NYSE:MA) and the businesses that accept consumer payments via those instruments is heating up again, as a flurry of lawsuits filed on both sides over a prior settlement regarding interchange fees jump-start the hostilities all over again.

What once seemed settled, really is not
The settlement reached last summer over swipe fees at first looked like a win for all, putting to bed scores of existing lawsuits on the issue, once and for all. But, soon after the announced pact, retail behemoths Walmart (NYSE:WMT) and Target (NYSE:TGT) began to voice their opposition to the terms.

Now, both retailers have joined with other businesses that have opted out of the settlement in filing their own lawsuit against Visa and MasterCard. A little over one week ago, Walmart, Costco, and Starbucks filed suit with 16 others alleging that the settlement abridges their rights to bring future actions against card issuers for colluding on the setting of interchange fees, and does nothing to prevent fee hikes by the card companies and banks that issue the cards.

Last Friday saw Target and a slew of others, such as JCPenney and Office Depot, file their own lawsuits, citing the same complaints as the Walmart crew. In response, Visa and MasterCard have sued right back, requesting a judge to rule in favor of the card issuers' fee structure and implementation practices.

A big headache for card issuers
Big banks like Bank of America and Wells Fargo were also listed, along with the card companies, since they are the actual recipients of these disputed swipe fees. Settlement of this issue would be nice for the banks, of course, but the whole conflict has become a gargantuan pain in the neck for the card issuers. Getting a court to make moot the very foundation upon which the two retailer groups are suing would take a great weight off of their shoulders, and allow a much tidier resolution to a problem that has been an annoying sideshow for the past several years.

As for the opting-out retailers, they will not have access to the more than $6 billion that the card issuers agreed to pay last summer, though they will have to abide by the new rules negotiated for the agreement. If the card companies and banks prevail in this latest suit, these retailers will likely be forced to accept the original terms of the pact in their entirety. If the issuers lose, all parties will surely be mired for many more years in the long-lived legal battle over interchange fees.

Fool contributor Amanda Alix has no position in any stocks mentioned. The Motley Fool recommends Costco Wholesale, MasterCard, Starbucks, Visa, and Wells Fargo. The Motley Fool owns shares of Bank of America, Costco Wholesale, MasterCard, Starbucks, and Wells Fargo. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.