David Cay Johnston:

Records showing how thoroughly the Internal Revenue Service audits big corporations and the rich, and how much it discounts the additional taxes assessed after audits, are being withheld from the public despite a 1976 court order requiring their disclosure, according to a legal motion filed last week in federal court in Seattle.

For decades, the information was given at no charge to a professor at Syracuse University, Susan B. Long, who made it available on the Internet at trac.syr.edu, with tools for people to conduct their own analyses.

Among other findings, Professor Long’s information has shown that in 1999 the poor were more likely than the rich to be audited.

David Burnham, co-director with Professor Long of the Transactional Records Access Clearinghouse, which collects raw government data, said the withheld information made it impossible to evaluate the intensity of audits. Mr. Burnham noted that the withheld data included figures that indicated how much auditors say is owed in extra taxes, but that the tax agency lets taxpayers negotiate down.

“It is simply impossible to evaluate the I.R.S. without this data,” Mr. Burnham said, “and they know it.”