Nottinghamshire County Council has been criticised for making accounts relating to a £850 million waste management contract open to public inspection.
It is in court as part of a judicial review hearing prompted by Veolia Environmental Services, which complained that disclosing details of its contract with the council breached confidentiality.
The council issued details of the contract to local resident Shlomo Dowen of the action group People Against Incineration because it believed that it was following the letter of the law by making all books, deeds, contracts, bills, vouchers and receipts relating to them open, including the commercial details of its contract with Veolia.
But Veolia complained to the High Court that it had gone too far.
It claimed that the disclosure of invoices indicating how much it charged for its services breached the firms right to confidentiality and seriously damaged its ability to compete with other contractors.
The company has asked Mr Justice Cranston to quash the councils decision to disclose such information.
A Veolia Environmental Services spokesman said: Our concern is that if commercially sensitive information is made public then it could give an advantage to our competitors at a time when we are working to secure the long-term future of our business and our workforce. Naturally, any business would be concerned if commercially sensitive information was made openly available to its direct competitors.
We already put a great deal of information into the public domain and audited reporting shows that in partnership with Nottinghamshire County Council we are delivering a consistently excellent service to Nottinghamshire residents.
In terms of accessibility to contractual information, we want to get the balance absolutely right and a court judgment will bring certainty and provide clarity to local authorities, the public and the waste management industry.
However, the council argues that it is required to do so by the 1988 Audit Commission Act, which gives local government electors the right to object to items in their authoritys accounts.