For decades, the government has used the “state secrets privilege— to block the use of evidence in litigation where revealing the evidence could harm national security. Under former President George W. Bush, the privilege was transformed into a weapon to shut down lawsuits challenging illegal or embarrassing government activity. President Barack Obama promised major changes.

This month, that promise rang hollow as the Justice Department filed a brief that could have been authored — in substance, if not in form — by Bush Attorney General Alberto Gonzales himself.

The state secrets privilege is a vital national security tool when properly used. But there is tremendous potential for the government to misuse the privilege to conceal wrongdoing or avoid accountability. In the first Supreme Court case to recognize the privilege — a lawsuit brought by the widows of the victims of a military plane crash — the government successfully suppressed the crash accident report, claiming that it contained sensitive information about military technologies. Decades later, when the report was declassified, it contained no state secrets — but it did contain powerful proof of government negligence.

In September, the Obama administration issued a new policy ostensibly designed to prevent such abuses. The policy allows the government to invoke the privilege only where disclosure would cause “significant— harm to the national defense or foreign relations — a higher bar than the previous administration used. It requires a team of Justice Department attorneys and the attorney general to approve agencies’ use of the privilege. And, when the privilege shuts down a lawsuit that alleges government misconduct, the policy creates two alternative mechanisms for accountability: review by an agency inspector general, and reporting to Congress.

But the most important needed reform was notably missing. The state secrets privilege is an “evidentiary privilege—: It is intended to shield particular documents, testimony or information from disclosure. The Bush administration, however, frequently argued that entire subject matters were off-limits, shutting down lawsuits before the evidence was even identified. The new policy allows the government to continue using the privilege to shut down lawsuits prematurely.

Administration officials assured open government advocates that this authority would be invoked rarely, if ever. Many advocates decided to withhold judgment, believing that the proof would be in the pudding.

We now have that proof. In the first test of its new policy, the Obama administration has asked a court to dismiss a case challenging illegal government wiretapping. Forecasting that the evidence needed to litigate the case would be privileged, the administration urged the court not to test this prediction by actually identifying and assessing the relevant evidence, but to simply shut the case down. Even more disturbing, the administration argued that the “very subject matter— of the case is a state secret. These are the same arguments the Bush administration made in case after case.

Given a policy that permits overbroad claims of privilege and a now-proven willingness on the part of the administration to use that authority, there is no longer any reason to wait. It is time for Congress to step in and take the necessary steps to curb abuses of the state secrets privilege. This will involve several key reforms.

First, Congress must ensure that courts do not shut down lawsuits without first determining that the evidence needed to litigate the case is privileged. In order to make this determination, the relevant evidence must be identified through discovery, and the court must assess each item of evidence to evaluate the government’s privilege claim.

Second, Congress must protect judges’ role as the final arbiters of whether the privilege applies — a role they cannot possibly perform unless they see and understand the evidence in question. Congress should thus require the government to submit the evidence to the judge for review behind closed doors. Such judicial review is a key safeguard against abuse, and there’s no reason to dispense with it. We trust federal judges to handle classified information in criminal cases; surely we can trust them not to leak secrets to North Korea or al-Qaida.

Third, Congress should consider ways to allow lawyers for the other side to participate in privilege determinations. After all, participation by opposing parties is at the heart of our system of justice; it is the best guarantor of getting to the truth. Precautions can be taken to make sure that national security is protected. For example, where needed, a judge could appoint special security-cleared counsel to represent the nongovernment party’s interests.

Finally, Congress should direct judges to look for ways to keep legitimate cases alive even if important evidence is deemed a state secret. One option is to require the government to create nonprivileged substitutes for the privileged evidence where possible, such as redacted versions or summaries. This technique has been successful in dealing with classified information in criminal cases.

Legislation introduced in Congress, the State Secrets Protection Act, would accomplish these steps and guard against abuses of the privilege. Momentum behind this legislation flagged after the administration announced its new policy, as lawmakers waited to see whether the policy would result in a new approach. But the House Judiciary Committee recently took up the legislation and passed it out of committee. The Senate should follow the House’s lead. It’s time for Congress to draw a line, once and for all, between valid privilege claims that keep our nation safe and misuses of the privilege that simply keep us in the dark.

Elizabeth Goitein is the director of the Liberty and National Security Project at the Brennan Center for Justice. Frederick A.O. Schwarz Jr. is the Brennan Center’s chief counsel. They are the authors of a book on government secrecy to be published by the New Press in 2012.