THE UNITED STATES remains the world’s leading jailer, with more than 2 million individuals locked up. The annual price tag is $50 billion.

Who are the individuals behind bars? What crimes were they convicted of and what penalties did they receive? What relationship is there between the rate of incarceration and the drop in violent crime? Are there more effective and inexpensive ways to deal with lawbreakers?

These and other questions would be tackled by a bipartisan commission proposed by Sen. James Webb (D-Va.). Republican and Democratic leaders would pick the 14 members of the National Criminal Justice Commission, including experts on law enforcement, prison administration, mental health and drug abuse. The commission, supported by the Fraternal Order of Police and the International Association of Police Chiefs, would have a budget of $5 million and would issue a report after 18 months. This approach is long overdue: The last comprehensive review of criminal justice was conducted roughly 45 years ago during the Johnson administration.

Yet Mr. Webb’s efforts were dealt a blow last week when Republicans in the Senate blocked consideration of the measure.

Sen. Kay Bailey Hutchison (R-Tex.) criticized the proposal for stomping on states’ rights. Sen. Tom Coburn (R-Okla.) deemed it unconstitutional. The National District Attorneys Association, which opposes the measure, wrote that the “federal government should neverbe in the business of auditing state and local criminal justice systems.”

These criticisms fall flat. The panel would only study the policies of local, state and national law enforcement entities and make recommendations about best practices. It would have no power to issue mandates. The federal government, which distributes federal dollars as incentives for states and localities to adopt best practices, has a legitimate need to know which policies work.

Some critics question whether a commission appointed by politicians will issue fair recommendations; a nonpartisan academic group may be better-suited for the task. Critics also worry that 18 months — the length of time the Johnson commission was up and running — is not enough time. These are points that should be addressed, but they are not valid arguments against conducting a review.