In court and in response to inquiries, intelligence officials have argued that disclosing the total spying budget would create pressure to reveal more spending details, and that such revelations could aid the nation's adversaries.

That argument has been rejected by many members of Congress and outside experts, who note that most of the Defense Department budget is published in exhaustive detail without evident harm.

The national commission on the terrorist attacks of Sept. 11, 2001, recommended that both the overall intelligence budget and spending by individual agencies be made public "in order to combat the secrecy and complexity" it found was harming national security.

"The taxpayers deserve to know what they're spending for intelligence," said Lee H. Hamilton, the former congressman who was vice chairman of the commission.

Even more important, Hamilton said, public discussion of the total budgets of intelligence agencies will encourage Congress to exercise "robust oversight."

The debate over whether the intelligence budget should be secret dates at least to the 1970s, said Loch K. Johnson, an intelligence historian who worked for the Church Committee investigation of the intelligence agencies by the Senate in the mid-'70s.

Johnson said the real reason for secrecy might have less to do with protecting intelligence sources and methods than with protecting the bureaucracy.

"Maybe there's a fear that if the American people knew what was being spent on intelligence, they'd be even more upset at intelligence failures," Johnson said.