A top Mexican university used AI to police its biggest exam ever. 150,000 students are now in limbo.

Daniel Fernando García Velázquez left his home in Veracruz and drove roughly 400 kilometers to Mexico City to sit UNAM's first-ever online entrance exam in June. UNAM, Mexico's National Autonomous University and the country's most prestigious public university, scored him 94 out of 120. That should have secured a seat in Communication and Journalism at the Aragón School of Higher Studies. He still does not know if he can start class on August 10.

He is one of roughly 147,000 applicants UNAM put on hold after an AI proctor it had just deployed flagged an unusual cluster of perfect scores and prompted the university to invalidate about 3,000 of approximately 150,000 tests (CNN). The cheating question is real. The whole cohort, not just the 3,000, is on hold while UNAM investigates.

UNAM administered the exam online for the first time in 2026, replacing an in-person test that historically required some students to travel hundreds of kilometers to reach a designated site. The online format came with a new layer of AI-based monitoring, a system designed to detect the use of AI tools and the leakage of exam questions, the two cheating vectors UNAM has named in its investigation. UNAM annulled roughly 3,000 results out of about 150,000 and suspended enrollment for the entire cohort while it investigated, according to NPR and The New York Times.

The wider failure is procedural. 147,000 non-flagged applicants are suspended alongside the 3,000 the AI caught, and UNAM chose to suspend enrollment broadly rather than attempt to separate the two groups before the August 10 semester start. Velázquez, who did not flag as a cheater, is suspended anyway. So is every other applicant whose test the university has not yet cleared.

UNAM traces back to the 16th-century Royal and Pontifical University of Mexico, was granted autonomy in 1929, and has produced a generation of Mexican presidents, scientists, and journalists. Its entrance exam is, for tens of thousands of high-schoolers, a single bottleneck that decides whether higher education at a public flagship happens at all. Putting a fall cohort on hold for a system-design review is the kind of move that puts the university's own prestige in escrow.

The political weight is now visible too. Mexican President Claudia Sheinbaum, herself a UNAM-trained physicist, has publicly suggested enlisting the attorney general to investigate how the cheating was organized and who profited from it. Mexican outlets report that rejected applicants are preparing a colectivo, a collective amparo or constitutional injunction, to challenge the annulment, alongside an individual re-review process the university has opened with a documented deadline (La Razón, ejecentral, El Imparcial).

UNAM's process has to clear 147,000 non-flagged applicants before August 10 or the cost of the integrity move falls on the wrong cohort. Other universities moving high-stakes exams online will hit the same wall unless they build the due-process leg before they turn the tool on.

UNAM's autumn semester starts on August 10. Velázquez and roughly 147,000 others are still waiting on a verdict.