This piece first appeared at Just Security.
As Congress prepares to vote in April on reauthorizing Section 702 of the Foreign Intelligence Surveillance Act (“FISA”), one of the main points of contention will be the government’s practice of conducting warrantless searches for Americans’ communications that are “incidentally” collected under the law. Critics of the practice (including the Brennan Center) have argued that it violates the Fourth Amendment and turns a surveillance authority that is intended to be targeted only against foreigners overseas into a tool for spying on Americans.
In its April 2025 annual surveillance report, the Office of the Director of National Intelligence (“ODNI”) reported that the FBI conducted 5,518 of these “U.S. person queries” in 2024 — a more than 90% decline over the prior year. According to a recent letter from a Department of Justice official, the number of such queries in 2025 was significantly higher — 7,413 — but still well below the levels seen in recent years. Opponents of reform point to this decline as evidence that the modest reforms passed by Congress in 2024 as part of the Reforming Intelligence and Securing America Act (“RISAA”) are working, and that further restrictions on queries are unnecessary.
In fact, the apparent decline masks a disturbing development. What the ODNI’s report doesn’t mention is that the FBI failed to track all of its U.S. person queries in 2024 and 2025 as required by law, meaning the total number of U.S. person queries in those years is not 5,518 or 7,413 — it’s unknown. And the failure to track was only one of the statutory violations that marked the FBI’s queries in the year following Congress’s enactment of RISAA. Warrantless searches for Americans’ communications are inconsistent with the Fourth Amendment and invite abuse under the best of circumstances, but the FBI’s post-RISAA querying practices don’t weaken the case for warrants — they strengthen it.
Background: Section 702 and Backdoor Searches
Section 702 authorizes the government to collect the electronic communications of foreigners located abroad without a warrant if a significant purpose of the collection is to obtain foreign intelligence. The legal justification for this warrantless surveillance program is that it targets foreigners, not Americans. But because Americans communicate with foreigners, surveillance under Section 702 inevitably sweeps in Americans’ phone calls, emails, and text messages, too. The Privacy and Civil Liberties Oversight Board has emphasized that “ordinary Americans may be in contact with Section 702 targets for business or personal reasons even if the Americans have no connection to, or reason to suspect, any wrongdoing by their foreign contacts and even when the government has no reason to believe the target has violated any U.S. law or engaged in any wrongdoing.”
If the government’s intent were to eavesdrop on the Americans whose communications it “incidentally” collects, it would have to obtain a warrant (for a criminal investigation) or a FISA Title I order (for a foreign intelligence investigation) to comply with the Fourth Amendment. And yet, once the government has warrantlessly collected data under Section 702, it regularly searches through that data for Americans’ communications — without obtaining a warrant or FISA Title I order. These U.S. person queries — often referred to as “backdoor searches” —create an end run around the requirements of the Fourth Amendment and FISA and have long been the most controversial aspect of Section 702.
In 2022, after years of resisting calls to disclose the number of backdoors searches performed annually, the FBI revealed that it conducted up to 3.4 million U.S. person queries of federated data systems that included Section 702 data in 2021 alone. The following year, after the FBI changed its data systems to require FBI agents to “opt in” to running queries against Section 702 data rather than having to “opt out,” the number of U.S. person queries reportedly conducted by the FBI dropped to around 200,000. Following a change in how the FBI counts queries — multiple searches using the same U.S. person term are no longer counted as separate queries — the number dropped again to 57,094 in 2023. Notwithstanding the downward trend, these numbers, even at their lower end, confirm that an authority nominally limited to targeting foreigners overseas is routinely used to access Americans’ private communications.
On several occasions, bipartisan sponsors have introduced amendments to close the backdoor search loophole by requiring the government to obtain either a warrant or a FISA Title I order to search the content of Americans’ communications collected under Section 702. The proposals include reasonable exceptions designed to accommodate legitimate security needs. In 2024, this proposal was defeated in the House by a single vote. Instead of a warrant requirement, Congress passed RISAA — a law that codified several practices, such as supervisory approval for certain queries, intended to improve internal FBI and Department of Justice oversight.
A year after RISAA’s enactment, the government reported that the FBI’s U.S. person queries were down to 5,518 in 2024. Already, opponents of reform are claiming this number as a victory and citing it as proof that a warrant requirement for U.S. person queries is unnecessary. They will likely make the same claim with regard to the 7,413 U.S. person queries recently reported for 2025.
But that’s wrong on two counts. First, these figures reflect only the number of known searches. The government has admitted that the FBI failed to follow statutory requirements for an entire category of U.S. person queries. Because the FBI neither tracked nor audited these queries as required by law, the total number of backdoor searches in 2024 and 2025 — as well as the overall compliance rate — remains unknown. Second, the number of backdoor searches has no bearing on the fundamental issue with them: they violate the Fourth Amendment and invite governmental overreach and abuse.
The Unrecorded Backdoor Searches
In August 2024, the Department of Justice’s National Security Division (“NSD”) “became aware” that the FBI was using a particular electronic tool known as an “advanced filter function.” When using this tool to retrieve the communications of particular foreign targets, FBI agents could select from a list of “participants” who were in contact with those targets and review those participants’ communications. Although this functionality enabled FBI agents to search for U.S. persons’ communications using terms associated with those persons — thus plainly meeting the statutory definition of “query” — the FBI did not treat the searches as queries and therefore did not track or count them.
It is unclear how long the advanced filter function was in use before the NSD discovered it. Moreover, after learning about the tool in August 2024 and notifying the FISA Court, the NSD took several months to “evaluate” whether these searches constituted queries, and the functionality was not disabled until an unspecified time in “early 2025.” The number of queries reported for any given year encompasses queries performed from December of the previous year through November of the reporting year. Accordingly, the reporting for both 2024 and 2025 — and potentially before then — is incomplete.
The failure to track U.S. person queries is only one of the violations that accompanied the use of this querying tool. Because the FBI did not treat these searches as queries, the NSD acknowledged that FBI agents likely did not comply with any of the other oversight requirements that RISAA imposed in an attempt to curtail abuses. Specifically, FBI agents likely did not obtain supervisory or attorney approval for U.S. person queries; obtain Deputy Director approval for any U.S. person queries falling within certain sensitive categories; or record the reasons for conducting the queries. For the same reason, the Department of Justice did not conduct the statutorily required audit of these queries. The NSD told the FISA Court that it “‘does not presently have access to historical data’ that would allow it to determine whether such queries were compliant.” In other words, it is unknown whether these queries had sufficient legal justification — or what abuses may have occurred while the oversight mechanisms were sidelined.
The existence of a querying tool that operated under the radar and outside of statutory constraints also generates concern that similar tools may exist — at other agencies or on other FBI systems— that have not yet been detected by internal overseers and/or disclosed. This concern is not hypothetical: recent reporting indicates that intelligence agencies are actively expanding their use of AI-assisted surveillance tools, raising questions about whether the FBI might employ automated query functions that effectively circumvent statutory oversight requirements. In addition to demanding answers about the FBI’s advanced filter function, Congress should require the government to identify the steps it is taking to ensure that other search tools used by the agencies that receive Section 702 data do not enable queries to escape the requirements of the law. Until those answers are provided (and made publicly available), arguments premised on reported declines in U.S. person queries must be viewed with skepticism.
Continued Necessity of a Warrant Requirement
Even if the number of U.S. person queries reported by the government in 2024 and 2025 could be taken at face value, that would not obviate the need for a warrant. For one thing, several thousand warrantless searches for Americans’ private communications would still represent a gross intrusion on U.S. persons’ privacy. The government is able to present that number as a success story only because the FBI conducted up to 3.4 million U.S. person queries in 2021. The shockingly low bar the government set in 2021 cannot be used as the measure of Americans’ rights.
Second, the constitutional concerns with warrantless searches do not turn on how many searches the government conducts. The core of the Fourth Amendment is review by a neutral magistrate. Internal agency self-policing simply cannot replace the vital check of judicial sign-off — a point amply reinforced by the FBI’s history of abusing U.S. person queries to search for the communications of protesters across the political spectrum, members of Congress, journalists, and campaign donors. As the Supreme Court remarked in a landmark 2014 Fourth Amendment case: “The founders did not fight a revolution to gain the right to government agency protocols.”
Courts are beginning to recognize the constitutional infirmities of the current system. In 2019, a unanimous panel of the Second Circuit held that U.S. person queries are separate Fourth Amendment events, distinguishable from the initial collection of foreign targets’ communications. The district court in the case then ruled that the backdoor searches the government had conducted were unconstitutional because they were not conducted pursuant to a warrant or an exception to the warrant requirement.
At a practical level, if the FBI indeed conducted “only” a few thousand warrantless searches for Americans’ private communications in 2024 and 2025, that would actually strengthen the case for a warrant requirement. When the number of annual U.S. person queries stood at more than 200,000, the government argued that a warrant requirement would be unworkable and overwhelm the courts. That argument is much less persuasive if queries have fallen by 97.5%. (The actual number of warrants required would be even lower, as most legislative warrant requirement proposals would allow the FBI to determine whether the U.S. person was in communication with a target before obtaining the warrant. By the government’s own statistics, this step would reduce the number of required warrant applications by anywhere from 62 to 98%.)
A warrant requirement would also solve a potential problem identified by the Department of Justice’s Inspector General in a 2025 report. FBI employees interviewed for the report expressed “concern” that “the extensive oversight” put in place in recent years “has caused ‘audit fatigue’ that has reduced the willingness of some FBI personnel to query Section 702-acquired information altogether.” These employees pointed to the “administrative burden” of obtaining attorney approval and keeping records of U.S. person queries, as well the concern that agents might be subject to disciplinary actions for running queries that turned out to lack sufficient justification.
The simplest way to address this purported issue — and the only way to do so without a resurgence of the querying compliance violations that have historically plagued the FBI — is to place the burden of gatekeeping searches where it belongs: with the courts. As one of us stated in recent testimony:
[A warrant requirement] would reduce the need for the multiple layers of internal oversight that have been established in a futile effort to replicate the function of judicial approval. It would also take away any motive for excessive caution; the only penalty if an agent submitted an application that turned out to lack sufficient basis would be the court’s denial of the application. Agents would be free to do their jobs — i.e., to vigorously pursue their investigations consistent with the law and their professional obligations — while the courts would perform their job of determining whether the government has a lawful basis for searching Americans’ private communications.
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In short, Congress should take little comfort from the numbers that the government reported in 2024 and 2025. The numbers are incomplete — and the actual number of U.S. person queries unknown — because the FBI engaged in a systemic violation of the internal oversight requirements Congress codified in RISAA. These violations, on top of the persistent and widespread violations that have marked Section 702’s operation since its inception, vividly illustrate the dangers of departing from the balance the Framers struck in the Fourth Amendment. It is high time for Congress to call this 18-year experiment in warrantless access to Americans’ communications a failure and to enact a warrant requirement for backdoor searches.
