Adrian Mutu has sounded his disappointment that his appeal against an order to pay former club Chelsea €17.17million (£14.7m) in damages has been rejected.
The Romania international, who is now at Fiorentina, was ordered to pay the sum by Fifa last year after he was fired by the Blues in 2004 for testing positive for cocaine.
Mutu believed the amount of money was not valid, but last week the Court of Arbitration for Sport dismissed his complaints.
The 30-year-old has admitted his annoyance that his appeal has been rejected and has hinted that he is not yet prepared to let the matter drop.
"I cannot fail to exercise my right to criticise a sentence that appears profoundly unjust," he said.
"I think I have amply paid for an error of youth which is light years away from the man and footballer I am now.
"Today after so much time, that error cannot be the basis of a demand for damages that seem to go beyond the realm of sporting sanctions, given that Chelsea unilaterally decided to terminate my contract.
"I am a sportsman but also, above all, a citizen of the European Union and I believe that sporting justice must respect the principles and fundamental rights of the community.
"So I will evaluate every possible initiative to protect my rights."