OTTAWA - Another battle has erupted in the House of Commons over the right of parliamentarians to see government information.

The Liberals have asked Speaker Peter Milliken to decide whether Prime Minister Stephen Harper's cabinet can withhold background studies on government legislation.

The Commons finance committee in November was denied the right to see government projections of corporate profits before taxes, and was refused a look at studies on the cost of Conservative changes to the criminal justice system.

Both are being withheld on the grounds they are cabinet confidences.

"Mr. Speaker, withholding the requested information from the committee does not serve the public interest," Liberal finance critic Scott Brison said Monday in the Commons on a motion of privilege.

"In fact, withholding this information impedes Parliament's ability to fulfil its duty to scrutinize the estimates and hold the government to account."

Brison noted that government corporate profitability forecasts have been published by the Finance Department in the past, and he argued that confidentiality on cost estimates shouldn't apply to legislation once it's been introduced and is in the public domain.

Tom Lukiwski, the junior Conservative House leader, asked for time to provide a "comprehensive response" to Brison's complaints and Milliken has agreed.

The Speaker ruled last April in the case of Afghan detainee documents that Parliament's right to request information is "unfettered" and cannot be circumscribed by the government -- even when it involves national security.

The finance committee, which is dominated by opposition MPs reflecting the minority government status, wants to examine the impact of Conservative corporate tax cuts and would like to see the anticipated price tag of 18 different pieces of criminal justice legislation.

Both are politically sensitive policy areas given the current $56-billion deficit and Conservative promises to balance the nation's books in five years.

A group of more than 500 doctors, criminologists, clinicians and health researchers wrote an open letter to the government this week highly critical of federal drug legislation they say is "not scientifically grounded."

"During these difficult economic times, this raises the question of why the federal government proposes to spend scarce financial resources on policies that have been shown to be expensive, ineffective and harmful," said the letter from the Urban Health Research Initiative.

The independent parliamentary budget officer, Kevin Page, has estimated just one of the government's crime bills alone, the Truth in Sentencing Act, will cost between $7 billion and $10 billion over the next five years as prison populations bulge and new prisons are required.

Public Safety Minister Vic Toews has provided a variety of figures for the cost of prison expansion, but none higher than $2 billion over five years.