This piece was originally published on Just Security, an online forum for analysis of U.S. national security law and policy.

A core national security law allowing the government to collect intelligence information—Section 702 of the Foreign Intelligence Surveillance Act—is set to expire at the end of the year. With the deadline looming, the debate in Congress over reauthorizing Section 702 now centers on a crucial issue: the FBI’s ability to search for clues in its databases.

The focus on this issue is important. There is a national security imperative for the FBI to review quickly and efficiently data that the government has lawfully collected when the bureau opens an investigation or identifies a new suspect, especially someone who may have links to terrorism or espionage. No one seriously questions this imperative.

But some critics (for example, here and here) of Section 702 have argued that the FBI should be required to obtain a warrant based on probable cause from the Foreign Intelligence Surveillance Court to query its Section 702 databases whenever the query concerns an American citizen or permanent resident (generally referred to as “U.S. persons”). Under current practice, the FBI is authorized to review its FISA data without a warrant, as long as the bureau follows specific court-ordered safeguards (called “minimization procedures”) and internal policies designed to protect privacy. Critics, however, consider such queries “backdoor searches” that circumvent the Fourth Amendment because they may reveal Americans’ communications.

In my view, this argument is based on a misreading of what the law requires and a basic misunderstanding of how national security investigations work in practice. First, from a legal perspective, Section 702 authorizes the government to target only individuals who it reasonably believes are not U.S. persons and who are outside the United States. The law expressly prohibits targeting Americans at home or anywhere else in the world. Even if the FBI has a compelling reason to believe that a U.S. person is involved in planning a terrorist attack, Section 702 still prohibits the government from using this authority to target the person for intelligence collection.

In all such cases, the FBI must first go to the FISC to obtain a court order based on a finding of probable cause to believe the U.S. person is an agent of a foreign power. Only then can the government target a U.S. person with a wiretap or search. In other words, the government may not purport to target a person overseas as a pretext for obtaining the communications of anyone in the United States. This prohibition on “reverse targeting” is strictly enforced by multiple layers of oversight across all branches of government, including a court-approved compliance regime, and there is no record of any government misuse.

Of course, in some instances, the communications of U.S. persons may be collected when they are in contact with lawful Section 702 targets, such as suspected terrorists overseas. This is no different from the incidental collection of communications of nontargets in the context of criminal wiretaps. For example, when a suspected mobster uses a wiretapped phone to order a pizza, both sides of the communication may be monitored and recorded, even though the pizza delivery person was never the subject of a court-authorized wiretap. And if the mobster called the pizza shop not to order a pizza, but as part of a money laundering scheme, the communication is evidence against everyone involved in the call. This is beyond dispute as a matter of constitutional law.

The same principle applies in the national security arena, where the importance of such collection is well-established. The government has been able to gain critically valuable intelligence about terrorist plots inside the U.S. by reviewing Section 702 data and identifying otherwise unknown individuals who were communicating and conspiring with terrorist targets overseas. This has always been an explicit goal and invaluable component of Section 702 collection.

How have federal judges viewed Section 702 collection in this context? Every court that has examined Section 702 has upheld the constitutionality of incidental collection. Last year, for example, the 9th U.S. Circuit Court of Appeals upheld the conviction of Mohamed Osman Mohamud for attempting to detonate a bomb in downtown Portland, Oregon. Mohamud had been in email communication with an overseas target of Section 702 and challenged the admission of the contents of his incriminating emails at trial. The 9th Circuit rejected his Fourth Amendment argument, concluding (and agreeing with another court decision on this issue) that “when surveillance is lawful in the first place—whether it is the domestic surveillance of U.S. persons pursuant to a warrant, or the warrantless surveillance of non-U.S. persons who are abroad—the incidental interception of non-targeted U.S. persons’ communications with the targeted persons is also lawful.” In the current legislative debate, this principle seems to be beyond dispute.

But critics of Section 702 have tried to take the argument a step further, claiming that even if such communications are lawfully intercepted, the Fourth Amendment requires the government to obtain a separate probable cause warrant before looking at the communications. This argument is off the mark, seeking to impose a mandate that the Constitution has never required—and that Congress should not impose now.

When the FBI (or National Security Agency or CIA) conducts a query of information it has lawfully acquired under Section 702—for example, using the email address or phone number of a U.S. person—this is not the initiation of a new surveillance or search protected by the Fourth Amendment and subject to the warrant requirement. It is the review of information that the agency has already obtained by lawfully targeting others and that now resides in its databases. The FBI is simply using a search term or identifier to narrow its search and find such information in order to further an authorized investigation. In one recent case, a federal judge agreed with experienced prosecutors that “[i]t would be perverse to authorize the unrestricted review of lawfully collected information but then restrict the targeted review of the same information in response to tailored inquiries.”

The FISC has directly addressed this issue and upheld the FBI’s practice of querying Section 702 data with terms that identify U.S. persons. The court had the benefit of briefing from experienced amicus counsel, who argued that the FBI’s approach violated the Fourth Amendment. The court concluded that the FBI’s practice—which followed court-approved minimization procedures that substantially limit the use and dissemination of the information derived from queries—met the requirements of the Constitution. The court found that the FBI struck a reasonable balance between the individual’s privacy interests and national security, even where the FBI conducted queries for evidence of crimes that were totally unrelated to the collection of foreign intelligence. By contrast, those who advocate locking this data away from investigators in the absence of a court order can point to no judicial precedent that directly supports such a restriction.

From an operational perspective, the FBI’s current approach also helps keep Americans safe. Requiring the FBI to obtain a warrant to review information it has lawfully acquired would interfere substantially with its ability to conduct national security investigations.

In a fast-moving terrorism investigation, for example, the ability of the FBI to focus on potentially dangerous suspects quickly is essential. A critical question at the outset of any national security investigation is whether potential suspects are part of a broader network or communicating with transnational groups. At the same time, it is also important for the FBI to swiftly rule out individuals who do not merit further investigation, so that investigators can wisely dedicate their limited resources. In considering the operational value of Section 702 to the FBI, Congress has the benefit of a bipartisan independent study. The Privacy and Civil Liberties Oversight Board, following a comprehensive review of Section 702, validated the law’s importance to the government’s counterterrorism efforts and, in particular, to the FBI’s ability to determine the identity and whereabouts of suspects here who are in contact with terrorists overseas.

Consider a hypothetical scenario involving an individual in the United States who is communicating with ISIS. The individual has become radicalized over the internet and is in email contact with an ISIS handler, who is a target of Section 702 collection. The ISIS handler has instructed the individual via email to drive a truck into a crowded area to kill as many people as possible. The FBI has no information about the individual until it receives an anonymous tip. The tipster says his neighbor has been angrily talking about U.S. policy in Syria and has said he wants to work with ISIS.

Under current practice, the FBI would likely move quickly to conduct an initial assessment and run database checks on the individual. The checks would include a query of Section 702 data using the individual’s name. This would reveal the contact between the U.S. person and a known ISIS terrorist and the substance of their communications, significantly increasing the importance and urgency of the investigation and leading to additional and more intrusive investigative steps.

But if critics of Section 702 prevail, the FBI would be required to get a warrant just to review its Section 702 databases. At this early stage of the investigation, where the FBI only has a vague tip from an unidentified neighbor, it almost certainly does not have enough information to establish probable cause. The FBI could spend days trying to interview more witnesses or use other investigative techniques, but it would not be able to see the crucial communications between the subject of the investigation and an ISIS operative. These email messages would sit cloaked in the FBI’s database, unavailable to the investigating agents. This scenario, which reflects recent attacks, highlights the danger of categorically excluding access to intelligence information that the government has in its possession.

More broadly, one of the first steps for agents in any serious investigation is to check the names of subjects against the information in existing files and databases. So, for example, in the ISIS scenario, the FBI would also quickly check to see if the name of the suspect appeared in any other FBI terrorism investigations and would be able to review the investigative reports in those investigations. These reports may include the substance of communications—as recounted by witnesses, for example—between the suspect and another investigative target.

This ability to review a conversation as captured in a report—a standard and uncontroversial investigative step—is essentially the same as the ability to review a lawfully acquired email message between a new suspect and the target of prior Section 702 collection. The call by critics of Section 702 to require a probable cause warrant to query Section 702 communications could apply to all incidentally collected information in the FBI’s databases, regardless of how the information was obtained. In other words, there is no principled or logical limit to the view of critics that the FBI should have to establish probable cause and get the permission of a judge to look at information it has already obtained lawfully.

Some proposals would permit the FBI to query its databases for connections based on metadata—for example address information—on a standard of proof lower than probable cause. These proposals, however, would still impose potentially dangerous and unwarranted restrictions on FBI investigations. The content of communications may be the only information that provides investigators with the details necessary to identify and disrupt attackers. But under these proposals, the substance of communications would remain unavailable to the FBI in the absence of probable cause. Further, these proposals would still require prior court approval for queries simply designed to find metadata information. There is simply no precedent for such a requirement when the FBI is querying information it has already obtained. And even under a lower standard of proof, the requirement for court approval still imposes substantial obligations on investigators. For any type of order, the FISC demands that the FBI prepare applications with care and rigor, and requiring judicial approval even for metadata queries is certain to impede investigators when speed is essential.

Finally, the argument that, in the absence of a court order, lawfully obtained Section 702 information should be beyond the reach of investigators is at odds with the lessons learned in the wake of the 9/11 attacks. The 9/11 Commission Report chronicles in detail the failure of the FBI and other intelligence agencies to analyze and disseminate information they had in their possession and the failure to share information because of perceived impediments, like the notorious FISA “wall” that prevented intelligence and law enforcement officials from collaborating. An enduring lesson of the review of the 9/11 attacks is that these failures contributed to the government’s inability to “connect the dots”—the fragments of information and other clues that may have led investigators to the 9/11 conspirators.

As the congressional debate culminates in the coming weeks, there are certain reforms to enhance transparency and oversight of Section 702 that merit serious consideration. But the proposals to impose new restrictions on the FBI’s ability to find and share Section 702 information ignore the lessons of 9/11 and run contrary to the operational imperatives of counterterrorism and other national security investigations.

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