In their High Court ruling that details of MPs' expenses should be disclosed, the panel of three judges said they had "no doubt that the public interest is at stake".
They added: "We are not here dealing with idle gossip, or public curiosity about what in truth are trivialities.
"The expenditure of public money through the payment of MPs' salaries and allowances is a matter of direct and reasonable interest to taxpayers."
Whether payments had been made to MPs within the rules, and whether the rules were appropriate, "bear on public confidence in our system at its very pinnacle, the House of Commons itself".
The judges described as "unrealistic" the Commons authorities' argument that the Information Tribunal had failed to take account of MPs' "reasonable expectations" that the details of their expenses would not be revealed.
They declared: "We can find no misdirection or other error of law which would justify interfering with the decision of the Tribunal."
The judges said it was "highly significant" that none of the MPs subject to applications had suggested that they claimed allowances on the basis that detailed information would not be disclosed.
Once it had emerged, as the Tribunal found, that the operation of the ACA system was "deeply flawed", public scrutiny of the details was "inevitable", and it would have been unreasonable of MPs to expect anything else.
Upholding the Tribunal's decision that MPs' addresses should be disclosed, the judges noted that many were available to the public in any event.
Details of property ownership were available from HM Land Registry.
Since one address of an MP was already in the public domain, ordinarily there would not be a sufficient reason for keeping a further address confidential - "particularly when scrutiny of the identity of second homes is part of the reason for disclosure of the information under consideration".
Rejecting the claim that revealing MPs' addresses should be prevented because of potential security threats, the judges said there was no evidence of any risk relating to the 14 MPs whose ACA claims were under consideration.
The judges upheld the Tribunal's ruling that privacy should only be allowed in the most pressing cases.
This was because the Tribunal had found that "the ACA system was so deeply flawed and the shortfall in accountability so substantial" that the necessity for disclosure had been "convincingly established".
The judges observed that, if the system was revised and there was more robust checking of MPs' claims to make sure addresses did exist and claims were not excessive, then the case for specific disclosure of addresses "may be rather less powerful".