Oil giant BP has lost a bid to avoid paying $15 million to Walmart for losses the retailer suffered due to its 2010 oil spill in the Gulf Coast.

On Tuesday, the U.S. Court of Appeals for the Fifth Circuit affirmed payments to five Walmart stores in Florida, Mississippi and Louisiana that made separate claims as part of a 2012 class action settlement aimed at compensating businesses with economic losses tied to the Deepwater Horizon oil spill. BP, which unsuccessfully challenged its own settlement in a legal fight that went all the way to the U.S. Supreme Court, has continued to petition the Fifth Circuit to review individual payments to certain businesses in a settlement now estimated to have grown to more than $10 billion.

Tuesday's ruling is among the largest payouts BP has challenged—although, on Wednesday, the Fifth Circuit affirmed a $27.4 million award to Mueller Copper Tube Company Inc., a copper tube production facility in Fulton, Mississippi, accused of having discrepancies between its financials and tax returns. Walmart also is among the most high-profile businesses to make oil spill claims in a claims process largely sealed from the public.

Susman & Godfrey partner J. Hoke "Trey" Peacock, in Houston, an attorney for Walmart Stores East L.P., did not respond to a request for comment, and BP's lawyer, David Weiner, a Washington, D.C., partner at Arnold & Porter Kaye Scholer, declined to comment.

In 2014, the Fifth Circuit rejected BP's attempts to unravel the settlement, which is separate from the $18.7 billion it reached with several government entities in 2015. BP's primary argument was that the settlement awarded businesses with no damages caused by the spill.

After the U.S. Supreme Court refused to take up BP's petition to review the Fifth Circuit's approval of the settlement, a claims administrator continued to respond to requests for compensation. BP has challenged some of those payouts through appeal panels, whose final decisions are reviewable by U.S. District Judge Carl Barbier of the Eastern District of Louisiana.

In appeals before the Fifth Circuit, court records have identified businesses anonymously by claim ID number—in Walmart's case, Claim ID No. 100354107. Yet, the names of some high-profile claimants, like the Tampa Bay Buccaneers and celebrity chef Emeril Lagasse, have gone public.

On Feb. 15, the Fifth Circuit vacated a 2015 administrative order mandating that all appeals from claimants to the settlement remain sealed. "This court has a strong presumption in favor of public access to all court documents," the appeals court wrote in a letter to lawyers for BP and Walmart.

In the Walmart cases, Barbier declined to review awards, which consisted of: $5.9 million to a store in New Orleans; $4.4 million to one in Waveland, Mississippi; nearly $3.7 million to a store in Destin, Florida; and $1.8 million each to stores in Panama City Beach, Florida, and Biloxi, Mississippi. In its response to BP's appeal before the Fifth Circuit, Walmart said it had nine stores along the Gulf Coast impacted by the spill but that two of them had claims rejected while Walmart withdrew a third. BP is challenging a nearly $1 million payment to a sixth Walmart store, in Pass Christian, Mississippi, based on whether it was a "startup business" because it closed from 2005 to 2009 following Hurricane Katrina. The Fifth Circuit heard oral arguments in that appeal last month.

In the five cases at issue in Tuesday's ruling, BP insisted that Walmart received too much compensation, because it changed its accounting practices one month after the spill. In particular, BP wrote, fixed and variable expenses differed from Walmart's accounting prior to the spill, making it appear that the stores were more profitable prior to the spill and increasing the amount of their potential compensation for losses.

As in other oil spill claimant appeals, BP attempted to argue why Barbier had abused his discretion by refusing to review the claims. In particular, BP argued, the appeal panels misapplied the settlement's terms as part of an "important and recurring issue" that arises when claimants change their accounting systems. Appeal panels also have divided on how to address such circumstances, BP argued.

Walmart called BP's allegations "speculative musings" and "meritless," noting it had accepted a reduction from the claims administrator's initial $17.4 million award.

The Fifth Circuit rejected BP's arguments, concluding that Walmart had provided adequate financial statements to the claims administrator.

"Although we are sympathetic, we are unconvinced by BP's pleas for more information," wrote Circuit Judge Leslie Southwick. "Before us is an exercise of judgment, not only by the district court but also by appeal panels and the claims administrator, in deciding when there is enough evidence under the terms of the settlement agreement to make an award."