The World Trade Organization reached a ruling Friday favoring Mexico against the US in a dispute over tuna labels.

According to Fox News WTO found that the "dolphin-safe" tuna labels based on Washington's requirement is unfair to Mexican tuna products. US labeling regulations have different requirements for every area where the fish is caught.

Mexico brought up the dispute in 2009. WTO ordered a review on the ruling of a panel that was created to settle that dispute. According to the WTO, the dolphin-safe labeling rules of US on tuna products still don't adhere to the regulations of that panel. Mexico's original argument was that the US rules were illegal since they limit trade. According to Mexico, it follows the international standard in catching tuna, making sure they don't accidentally capture dolphins.

Mexico News Daily reported that millions of dolphins used to be killed in the process that fishermen used to catch yellow fin tuna. Mexican fishermen used to set their nets on dolphin schools to catch tuna and release the by-catch dolphins right after. However, Mexico has established conservation efforts to set the dolphin fatalities below the threshold that the US has set. Dolphin deaths went down to 1,000 every year from 150,000 since 1950s.

The ruling is now final and Mexico has sought compensation for losses accrued in the span of twenty years. 

"The Appellate Body concludes that the United States has not brought its dolphin-safe labeling regime for tuna products into conformity with the recommendations and rulings of the (WTO's dispute settlement body)," the WTO said in its 144-page ruling, according to a report by Reuters.

The United States is disappointed with this most recent report," said U.S. Trade Representative's office general counsel Tim Reif.

The ruling is final, which means Mexico could make retaliation claims against US exports if the US rules are not in line with WTOs ruling.