Arla and its Scottish subsidiary, Claymore, appealed to the Competition Appeals Tribunal (CAT) after the OFT threw out their complaint that Scotland's leading dairy processor, Wiseman, was abusing its market position.
The firms accused Wiseman of targeting Claymore's middle-ground customers with offers for exclusive deals and 'below-cost' prices.
CAT said it had "serious doubts" about crucial aspects of the OFT's investigation; namely Wiseman's average costs and allegations that it offered 'below-cost' prices to Claymore's middle ground customers.
The appeals body criticised some of Wiseman's policies and said they presented a serious case for investigation. It stopped short of demanding a new investigation, but said it hoped "the OFT would take a firm line on such practices in the future".
Yet Arla said it was still keen to pursue the case both on principle and in order to recover costs.
The dairy processor said it would treat the investigation as re-opened after CAT announced it was "setting aside" the OFT's 2002 ruling. The firm said it would be making new submissions to the OFT.
However, CAT said that the allegations now date back more than six years, and "it is for the OFT to decide what, if any, further action should be taken".
Wiseman has already issued a statement implying that CAT's refusal to send the investigation back to the OFT means it is closed.