For 115 years, the most important test in a Mexican teenager’s life was guarded by a person at the front of the room — a watch, a clipboard, and two eyes that knew what a cheater looked like. This spring, the National Autonomous University of Mexico decided a webcam and an algorithm could do the same job, at scale, for a fraction of the sweat. The webcam watched nearly 160,000 faces. The algorithm, by the university’s own numbers, caught almost none of what it was hired to catch. And now the bill has landed on the wrong people: roughly 58,000 students, most of them honest, are being sent back to the starting line to take the exam again — in a room, on paper, under a human’s eye.
This is not the usual AI-failure story, the one about a model that forgot a fact or invented a footnote. This one happened where trust matters most. An institution handed a machine a job the machine could not do, then turned around and made the innocent prove their innocence a second time. The guilty get a do-over by default. The honest get a punishment by default. Sit with that for a second.
Leonardo Lomelí — the Rector Wanted Fairness, So He Handed the Exam to a Machine
UNAM moved its entrance exam online this year for a reason that sounds noble on a press release: equity. For decades, applicants from across Mexico had to travel to the capital — sometimes hundreds of miles — just to sit the test. An online exam, the thinking went, would open the doors of the country’s most prestigious university to kids who could never afford the bus fare to Mexico City. So the exam went remote for the first time in the university’s modern history, and nearly 159,000 young people logged in.
Guarding them was the modern arsenal: a “lockdown” browser that blocks copy, paste, and every other window, plus an AI-powered proctoring system watching every webcam with voice and facial recognition, scanning for a second person at the desk, a phone, an earpiece, or an applicant who wandered off camera. One human supervisor was assigned to every 150 test-takers, sitting behind a wall of alerts. The road to the worst exam scandal in the university’s modern history was paved, as these roads usually are, with the best of intentions.
The Territorium Proctor — It Watched 160,000 Faces and Missed Almost Everything
When the results came back, they did not read like a result. They read like a typo. Between 2021 and 2025, about 3.5 percent of applicants scored 100 or higher on the 120-question test. This year, 16.3 percent cleared that bar. At the very top, the jump was uglier: the share scoring 110 or higher went from under one percent to 5.5 percent, a sixfold leap. In medicine, the most cutthroat track in the region, nearly 30 percent of applicants hit 100-plus — against 9 percent the year before. Nobody got that much smarter in twelve months. The locks simply were not locked.
The university’s own audit confirmed the leak. It annulled two percent of the tests — 3,174 exams — for identity impersonation, outside help, and AI use. But that is only the number they could prove. A technical reviewer told The New York Times that nearly half of the exams — around 75,000 tests — could have involved some degree of cheating. Questions leaked and were even sold online while the exam was still open in May and June. The machine was hired to be the referee. It turned out to be a turnstile with a broken gate.
Raul Rojas — the Mathematician Who Counted and Found Half the Room Cheating
Raul Rojas, the Mexican-born AI researcher, did the arithmetic the university should have done before it ever switched on a webcam. Speaking to NPR, he said statistical modeling pointed to almost half of the students cheating while the exam was online. Half. The tips had been circulating for weeks before the test went live: position a second monitor just outside the webcam’s frame with ChatGPT open on it, hide an earpiece under your hair, or hire somebody to sit the exam off camera entirely. The proctor could watch a face; it could not watch a room.
That is the quiet lesson underneath the scandal. Cheating did not get harder when the exam went online — it industrialized. The same machinery meant to make the test tamper-proof handed the cheaters a whole new supply chain, and the proctor software was the one thing in the loop that never understood what it was looking at.
Claudia Sheinbaum — When Half a University’s Results Look Forged, the President Reaches for a Prosecutor
The debacle did not stay on campus. It became a national scandal, the kind that puts a president in front of a microphone. Claudia Sheinbaum said support for the university was always on offer, but that if a crime had been committed it was a matter for the prosecutor’s office — a carefully worded sentence that quietly opens the door to a criminal investigation. UNAM had already filed a criminal complaint in July over the fraudulent services allegedly sold to applicants and their families, from leaked answer keys to stand-in test-takers. A university exam has never needed a prosecutor before. This one does.
The Honest Applicants — Do Everything Right, and Take the Test Again Anyway
Now comes the part nobody wants to say out loud: the fix punishes the people who did nothing wrong. The expert commission’s answer is a “control exam” — a do-over, in person — for everyone who secured a spot, and for everyone who would have been admitted since 2021 on minimum scores. About 58,000 people are caught in that net. Rector Leonardo Lomelí apologized to the applicants who had won their places fairly but would still be called back to resit, arguing the retest was the only way to keep admission fair and certain. The honest kid who studied for a year, sat the screen, followed every rule, and finally got the letter she wanted now gets to prove herself again, because a webcam could not tell her apart from a fraud. Equity was the goal. Equity is now the apology.
Hundreds of applicants took to the streets in Mexico City, blocking major thoroughfares, and the academic year has already slipped from August 10 to August 31. More than 150,000 applicants were competing for just under 22,000 places, and the scandal has thrown every one of those places back up in the air. The university that promised a fairer gate has, for a season, replaced the gate with a revolving door — and the ones being spun around are the ones who never broke a rule.
The next time UNAM sits its exam, there will be no algorithm in the room. There will be paper, a clock, and a human being with eyes — the technology the university spent a century trusting, and the one it now has to return to, because the machine hired to be the adult in the room turned out to be the easiest mark in it. The proctor had one job. It watched.
Sources: Ars Technica, The Guardian, CNN.