Britain’s House of Lords ruled yesterday that Mercury Communications Ltd has the right to ask a court to interpret phrases in its interconnection agreement with British Telecommunications Plc in the area costs and overheads. The ruling allows Mercury to challenge the view of the Director General of Telecommunications that Mercury should pay a due proportion of British Telecom’s total costs and overheads – Mercury claims that the Director General should look only at the marginal and additional costs incurred by British Telecom in providing services to Mercury. Giving judgement, Lord Slynn of Hadley said, There is no issue as to whether Mercury is right as to its interpretation of the phrases in dispute. The sole issue is whether Mercury can raise these questions by the procedure which it has adopted or at all, he said.The four judges sitting with Lord Slynn all agreed.