On September 29, DHS’s Office of Inspector General (OIG) — the department’s internal watchdog — issued a report, “In FY 2021 — FY 2024, ICE Took Limited Action on Nonimmigrant Overstays, Including Those Deemed High Risk to National Security”. It examines how ICE made just eight lead-driven arrests of “overstays” — nonimmigrants who entered legally but failed to depart as required — largely due to Biden-era enforcement restrictions. That’s a major issue, given that one estimate suggests there may be up to six million illegal-alien overstays in the United States. Even more concerning is the key takeaway from that report: “foreign nationals who potentially posed threats to the United States remained at large despite their illegal status”.
“Immigrants” and “Nonimmigrants”
While everyone here who isn’t a citizen of national of the United States is an “alien” as defined in section 101(a)(3) of the Immigration and Nationality Act (INA), section 101(a)(15) of the act further divides aliens into two subgroups: “nonimmigrants” who are admitted for a specific purpose and either for a given period of time or pending an explicit event; and “immigrants” — essentially every other alien present here, legally or not.
The largest of those nonimmigrant classes are tourists and aliens briefly present for business (section 101(a)(15)(B) of the INA) and foreign students (section 101(a)(15)(F) of the INA), but nonimmigrant classes also include certain other aliens on temporary, employer-sponsored U.S. work visas (“H-1Bs”), fiancés of U.S. citizens (“K-1s”) coming to get married, and even fashion models (“O-1s”).
Nonimmigrant Visa Issuances Abroad
U.S. Department of State consular officers issue nonimmigrant visas abroad, and as DHS OIG explains, they cranked out more that 31 million of them between FY 2021 (the first partial year of the Biden administration) and FY 2024 (the last full fiscal year of that administration).
As the inspector general explained in an earlier September 2025 report, however, the State Departmentr issued “more than 12 million nonimmigrant visas” (emphasis added) between March 2020 and March 2024 to foreign nationals abroad “without conducting in-person interviews or collecting fingerprints”.
The Covid-19 pandemic drove that decision, but it was a dangerous gambit given: (1) fingerprints are a key biometric, and the final report of the 9/11 Commission highlighted the importance of “biometric screening systems” to U.S. security; and (2) as my colleague Steven Camarota revealed in 2002, three of the 9/11 hijackers “never had any contact with a consular officer” before they received their visas, thanks to the odious “Visa Express” program.
As Camarota explained: “Without having an in-person interview, the issuing officer cannot be sure that the person applying for the visa is actually the person named in the submitted documents and application. All varieties of deception and fraud become much more difficult to detect.”
Inspections at the Ports
Foreign nationals must clear two hurdles before they’re admitted to the United States as nonimmigrants, however, and obtaining the required visa abroad is just the first.
Once they arrive, they are screened again by an immigration officer from CBP’s Office of Field Operations (OFO) at U.S. ports of entry, who inspect those aliens to determine whether they are admissible to this country.
Unless that alien is “clearly and beyond a doubt entitled to be admitted”, the CBP officer will either expel the “applicant for admission” through “expedited removal” (under section 235(b)(1) of the INA) or detain the alien under section 235(b)(2)(A) for removal proceedings, wherein an immigration judge determines whether the alien is admissible.
As OIG explained in that September 2025 report, however, CBP officers conducting inspections at the ports “were unaware that some foreign nationals had not been fully screened by DOS [Department of State], thereby missing an opportunity to conduct enhanced screening and inspection prior to admission to the United States”.
In other words, millions of foreign nationals abroad were inadequately vetted before being given nonimmigrant visas they then presented to OFO immigration officers at U.S. ports of entry who were unaware of that prior inadequate vetting, and thus didn’t know those aliens required additional scrutiny before being “lawfully” permitted to enter the United States.
Tracking Visa Overstays
Section 110 of the Illegal Immigration Reform and Immigrant Responsibility Act of 1996 (IIRIRA) gave the then-Immigration and Naturalization Service (“INS”, the predecessor DOJ agency to CBP and ICE in immigration enforcement) two years to:
develop an automated entry and exit control system that will— (1) collect a record of departure for every alien departing the United States and match the records of departure with the record of the alien’s arrival in the United States; and (2) enable the Attorney General to identify, through online searching procedures, lawfully admitted nonimmigrants who remain in the United States beyond the period authorized.
INS failed to meet that two-year deadline, prompting Congress in section 414(a) of the (post 9/11) USA PATRIOT Act of 2001 to direct the agency to “fully implement the integrated entry and exit data system for airports, seaports, and land border ports of entry” as required by section 110 of IIRIRA “with all deliberate speed and as expeditiously as practicable” — legislative-speak for “we’re serious”.
In response, INS developed the Arrival and Departure Information System (ADIS), now managed by CBP, which “consolidates data from a variety of systems to create a unique person-centric record with complete travel history”.
As the agency has explained, however:
Determining lawful status requires more than solely matching entry and exit data. For example, a person may receive a six-month admission from CBP upon entry, and then he or she may subsequently apply for and receive from [USCIS] an extension of up to six months. Identifying extensions, changes, or adjustments of status are necessary steps to determine whether a person has overstayed their authorized period of admission.
To get a better idea of which nonimmigrants are overstays and which aren’t, therefore, CBP has further refined ADIS to aggregate various data, including the date and class of the alien’s admission, any updates or changes to the alien’s immigration status, and the date of the alien’s departure from the United States, if any.
ADIS is under the umbrella of DHS’s broader “Entry Exit & Biometrics Programs”, and to fulfill the “exit” part of its statutory screening mandates, the department in October 2025 published a final rule to implement a “system that compares biometric data of aliens collected upon arrival with biometric data collected upon departure” — 29 years after Congress gave it and its predecessor two years to do so.
Winnowing Down Potential Overstay Threats
There are two types of nonimmigrant overstays as identified by CBP: those whose departures were “recorded after their authorized period of admission expired”, who are referred to as “out-of-country overstays”; and others, “for whom no departure was recorded (suspected in-country overstays)”.
Nobody needs to find out-of-country overstays (because they’re now gone), but as OIG explains, CBP “generates daily overstay lists” of the ones suspected of still being here and “shares them with ICE for further review, analysis, and validation”, placing the overstay ball in that agency’s enforcement court.
Those daily leads go to the Counter Threat Lead Development Unit (CTLD) in ICE’s Homeland Security Investigations (HSI) directorate, which runs background checks on the aliens using 20 different information systems, including DOJ’s National Crime Information Center database (NCIC) and the National Law Enforcement Telecommunications Systems (NLETS), the latter “a telecommunications network that facilitates the sharing of criminal justice and public safety information between member agencies across the United States and Canada”.
“Based on these checks”, OIG notes, “CTLD reviews and assigns a risk rating to each lead for potential future investigatory and enforcement action” based on various factors, including the alien’s age, country of origin, and hits in the National Counterterrorism Center’s (NCTC’s) Terrorist Identities Datamart Environment (TIDE), both of which I have recently discussed at length.
CTLD then rates overstays who may pose “the highest threat to national security or public safety” as “Priority 1”, and “assigns Priority 2–9 ratings to progressively less dangerous overstays. Overstays who are not flagged based on any of” those factors “are deemed the lowest risk and receive a Non-Priority 10 designation”.
Those Priority 1 through 9 aliens are then sent by CTLD to the HSI offices best positioned to investigate, find, and arrest them. (Non-)Priority 10 aliens, on the other hand, are sent to immigration officers at ICE’s Enforcement and Removal Operations (ERO) directorate “for monitoring and potential enforcement action”.
The Deleterious Impact of Biden-Era Enforcement “Priorities”
While CLTD may recognize 10 types of aliens as overstay “priorities”, DHS under the Biden administration was much more modest: It only had three alien priorities for ICE enforcement actions.
Specifically, in September 2021, Biden’s DHS Secretary Alejandro Mayorkas issued his “Guidelines for the Enforcement of Civil Immigration Law” (the “Mayorkas memo”), essentially immigration-enforcement restrictions that I have analyzed at length elsewhere because of the deleterious impact they had on ICE’s ability to arrest, detain, prosecute, and remove deportable aliens during the last administration.
That memo identified three classes of aliens as “priorities” for ICE immigration enforcement: “threats to national security” (terrorists and spies); “threats to public safety” (criminals); and “threats to border security” (recent illegal entrants).
The recent-illegal-entrant priority was essentially eyewash, and not all removal criminal aliens were to be considered a priority for enforcement under the Mayorkas memo.
That’s because the memo required ICE agents and officers to also consider (irrelevant) “aggravating” and “mitigating” factors before taking “enforcement action” against criminal aliens deemed a threat to public safety, a term that applied to every step in the removal process, from investigating suspected removable aliens to prosecuting and deporting them.
“Aggravating factors” (logically) had to do with the gravity and harm of the alien’s criminal activity, but the “mitigating” ones (illogically) ran the gamut from the alien’s “advanced or tender age” and physical and mental condition to the “impact of removal on” the alien’s family in the United States and whether the alien or any member of the alien’s immediate family had ever had a government job.
Not surprisingly, ICE enforcement actions plummeted following the issuance of that memo and (even more restrictive) prior Biden-era policies, so it’s not for nothing that OIG highlighted the Mayorkas “guidelines” in its latest report.
The OIG’s Latest Report
ADIS proponents contend the system “produces significant cost avoidance benefits to the Nation that include enhanced border security and enforcement of U.S. immigration laws by serving as the Department's primary provider of overstay status and biographic identity services” and by “reducing the time ICE takes to act on an overstay from 45 days to 15 or fewer days”.
That’s only true, of course, if ICE actually “acts on an overstay” thanks to a CBP lead, which according to the latest OIG report rarely — and by “rarely” I mean almost never — occurred between FY 2021 and FY 2024.
Throughout that time period, HSI received 3.145-plus million overstay leads from CBP and categorized 104,049 of them (3.3 percent of the total) as Priority 1 through 9 due to “potential national security and public safety concerns”.
HSI held on to 204,000-plus of the remaining Priority 10 leads for further review, but the rest, more than 2.8 million CBP overstay leads (90.2 percent of the total), went to ICE ERO for it to take “potential enforcement action”.
Most saliently, as OIG explained, of those 104,049 Priority 1 through 9 leads, just 21,885 were deemed “viable for investigation by ICE” — that is they fell within ICE’s enforcement priorities — resulting in just 496 investigations (roughly 2 percent) “and the arrest of eight foreign nationals.” (Emphasis added.)
Worse, as per the inspector general: “Of the 1,769 viable Priority 1 leads, HSI initiated only 84 investigations (about 5 percent), resulting in two arrests.” So much for the “worst of the worst”.
As for the 2.8 million CBP overstay leads that weren’t either prioritized by HSI or held for its further review that were sent to ICE ERO “for monitoring, potential investigation, and enforcement”, they resulted in just five investigations (for potential public safety threats) and only two alien arrests.
That’s just 12 arrests out of more than three million leads, which is not much of a return on the taxpayers’ investment.
To Be Fair and Clear
In the interest of fairness, not all of the 3.145-plus million CBP overstay leads represented nonimmigrant aliens who failed to depart in a timely fashion.
Some “suspected in-country overstays” are aliens who did depart as required, but whose departures weren’t recorded because it’s taken DHS nearly three decades to finally issue a rule implementing an effective exit-tracking system.
That’s especially true for aliens who left via the Northern (Canada) and Southwest (Mexico) land border ports, where aliens have traditionally departed without encountering a CBP officer.
But given that the Pew Hispanic Center reported in May 2026 that, “As much as 45% of the total unauthorized migrant population entered the country with visas that allowed them to visit or reside in the U.S. for a limited amount of time” and overstayed, and that my CIS colleagues estimated there were about 13.5 million illegal immigrants here as of July 2026, ICE could have been taking “enforcement action” against millions of nonimmigrant overstays between FY 2021 and FY 2024, the period analyzed by OIG, but didn’t.
And to be clear, HSI during that time also arrested 263 nonimmigrant overstays from CBP leads initiated in prior years and arrested an additional 183 overstays as a result of its other investigations, while ERO made 16,458 arrests of nonimmigrant overstays that weren’t based on CBP leads — 16,904 additional ICE overstay arrests between FY 2021 and FY 2024.
Put the Blame on Mayorkas
Still, even counting those arrests, ICE action against nonimmigrant overstays was all-but a dead letter under Biden, and likely gave few aliens considering overstaying their visas any qualms about doing so.
And to again be clear, while OIG admits that “challenges verifying addresses and locating the foreign nationals present in the United States” and resource constraints impeded ICE’s ability to arrest and remove more overstays between FY 2021 and FY 2024, the DHS watchdog puts the lion’s share of the blame on Biden and Mayorkas:
ICE conducted few nonimmigrant overstay lead-initiated investigations and arrested even fewer foreign nationals who stayed beyond or violated the terms of their admission because of the September 2021 policy that directed ICE’s limited resources only to leads posing a threat to national security, public safety, and border security.
To recap, OIG reports that CBP sends ICE hundreds of thousands of suspected nonimmigrant overstay leads annually, but thanks to Biden-era enforcement restrictions, those leads resulted in just eight ICE arrests between FY 2021 and FY 2024, and as a result, aliens “who potentially posed threats to the United States remained at large despite their illegal status”.
Just when you think you know how bad immigration enforcement was under the last administration, the news manages to get worse — and even scarier. Perhaps then-Secretary Alejandro Mayorkas forgot he was in charge of the Department of Homeland Security — or maybe he had some more pressing concern than public safety in mind.