"Providing so-called free reports is not without eventual higher costs to the consumer," Trans Union said.
Trans Union won the contest and three years ago began issuing credit reports as part of the joint venture with the banks.
Officials at Trans Union said the credit bureau gets 45,000 to 50,000 calls a month from people complaining that their accounts have been taken over.
The company now crunches all data for Trans Union.
Trans Union said it would appeal.
(Trans Union and Experian are expected to follow suit soon.)
A trade commission official said Trans Union might have changed its marketing practices in that regard while the Government's lawsuit was pending.
A credit card company, for example, will give Trans Union a description of the sorts of people it wants to solicit.
Trans Union will then sell the company a list of names of people who meet the criteria.
When the trade commission first sued Trans Union in 1992, another administrative law judge issued a summary judgment against the company.