A Law Society council member has admitted to five breaches of professional rules in relation to his dealings with the miners' compensation scheme.
Glyn Maddocks, council member for the West Country and Gwent and a partner at Welsh firm Gabb and Co, was fined £15,000 at the Solicitors Disciplinary Tribunal (SDT) and ordered to pay the costs, estimated to be £60,000.
Maddocks' firm also agreed to repay money that had been deducted from miners' damages and paid instead to claims company IDC - an amount of less than £100 per claimant.
This is the third victory for the Solicitors Regulation Authority (SRA), which brought the proceedings.
Antony Townsend, the SRA's chief executive, said solicitors who fail to repay "will not be tolerated by the public, the SRA or the profession".
A Gabb and Co spokeswoman said the firm has always acted in good faith and never profited from any deductions made. She added that in 1999 Maddocks unknowingly misinterpreted the practice rules, but his intention was to achieve the best result for his clients.