More and more schools, universities and exam boards ask us about frequency detectors in exams. The question always arrives the same way: “the teachers want to buy one, is that legal?”. The short answer is yes, with conditions. However, the problem is almost never the device itself. It is the missing rule and the protocol nobody wrote down. Here we explain how students cheat today, what Spanish law says and how to deploy these units without creating a privacy problem.
In this article we will discuss...
From the crib sheet to the AI earpiece: how students cheat today
Cheating has always existed. However, technology has changed the scale of the problem. First came the phone in the pocket. Then the smartwatch that shows messages on the wrist. Today the catalogue looks different: nano earpieces that only come out with a magnet, cameras hidden in pens and smart glasses that record the question sheet.
Artificial intelligence made the decisive leap. A pair of glasses only has to transmit the paper, and an assistant dictates the answers straight into the ear. In other words, students no longer need an accomplice who masters the subject. In fact, smart glasses are rented by the hour in the United States. That is why the College Board banned them from the SAT in March 2026.
In Spain the phenomenon arrived earlier than most people think. Galicia has used detectors since 2019: teachers walk the rooms at random and, if there is a signal, they file a formal report. Aragón, Catalonia and Murcia joined them in the 2026 university entrance exam. Moreover, other regions have asked for funding to do the same. In short, frequency detectors in exams are now routine in the most closely watched test in the country.
Why schools buy frequency detectors in exams
The reason is simple: human invigilation no longer sees the device. A teacher spots a phone on the desk, but not a three-millimetre earpiece inside the ear. That is why many schools see frequency detectors in exams as a way to “see” the invisible.
Moreover, there is a reputational factor. An exam that cannot be guaranteed loses its value. This affects universities and public-competition boards. It also affects schools, which assess minors and must defend their marks in front of families. In that context, buying a detector looks like the obvious answer. And it can be, provided it is used well.
Is it legal to use frequency detectors in exams?
Yes, as long as the device is a passive detector. In other words, a unit that only receives radiofrequency signals and warns when it finds them. The warning arrives through light, sound or vibration. Common commercial models claim coverage from 1 MHz to 6.5 GHz, so they span mobile telephony, Wi-Fi and Bluetooth. They do not transmit, they do not block and they do not identify anyone.
Detectors yes, jammers no
Here lies the red line, and it deserves a literal quotation. Article 82.4 of Spanish Act 11/2022 on Telecommunications bans importing, marketing, installing, holding, commissioning or using “any equipment with functionalities for the intentional generation of interference”. Only narrow public security and defence scenarios escape that ban. Article 106.9, in turn, classifies the same conduct as a very serious infringement.
Notice a nuance that almost nobody reads. The Act does not talk about “jammers”, but about any equipment able to generate interference intentionally. Therefore the commercial name is irrelevant. A school can never install one, however good the intention. Blocking the signal affects everyone, emergency calls included.
Frequency detectors in exams, by contrast, interfere with nothing. That is why their use is lawful. That said, a radio receiver is radio equipment too. Consequently, it must carry CE marking and an EU declaration of conformity under Royal Decree 188/2016. Ask the seller for that declaration before buying, above all when the model comes from a marketplace.
What a detector does not do
Two myths deserve to be dismantled. First, the detector does not “listen” to anything: it reaches no calls, no messages and no content. It does not identify the handset or its owner either. It merely measures radio energy nearby.
Second, frequency detectors in exams are not infallible. A phone that is switched off or in flight mode does not transmit and therefore goes unnoticed. By contrast, the classroom Wi-Fi, the digital whiteboard or the teacher’s own phone do produce a signal. Consequently, an alarm tells you that something is transmitting in the area. It does not prove that a particular student is cheating.
The price of the device is a legal argument too
The cost of frequency detectors in exams usually goes unnoticed, and that is a mistake. Marketplaces offer models for ten or twelve euros. The professional units Galicia uses, by contrast, cost around two thousand euros each. The difference lies not only in the finish, but in selectivity, calibration and false positives.
That is where the risk appears. Imagine the school buys the cheapest model and then tries to annul an exam on the strength of its beep. Proportionality collapses on its own. That is why we recommend recording in writing why that unit was chosen and what margin of error the school accepts.
Privacy: what the GDPR says about frequency detectors in exams
This is the part that raises the most doubts and, curiously, the least problematic one when it is done well. A sweep with the detector processes no personal data. The device records nothing and links the signal to nobody. Processing appears later, when the school connects a detection to a specific student and documents an incident.
The legal basis depends on who runs the exam
Here it pays to be more precise than usual, since not every examiner sits in the same position. The twenty-third additional provision of the Spanish Education Act lets schools process the data needed for their educational function. On that footing, a school can rely on article 6(1)(e) GDPR, that is, on a public interest task with its own statutory cover.
However, that route does not fit everyone. A private exam-preparation academy is not a school under the Education Act. Therefore it must look for its basis in the performance of the teaching contract or in a well-documented legitimate interest. Universities, in turn, rely on their own rules and on the terms of each call.
All three cases share one feature. Families and students need not give permission for frequency detectors in exams. They do need to be informed, usually through the school rules or the terms of the test.
The limits come from the Constitution, not from the GDPR
This is the most common framing error. A school may ask a student to show and hand over a device, because that fits the school rules and the AEPD guidance for schools. However, it may not search bags, frisk anyone or reach the content of the phone.
Data protection law does not draw that line. Article 18 of the Spanish Constitution does: personal privacy and the secrecy of communications. The Constitutional Court has extended that protection to the digital environment of the device. Therefore, even when the student is cheating, the content of the phone stays beyond the teacher’s reach.
Finally, minimisation. If no device appears, nothing gets written down. A file saying “the detector beeped near the student” is personal data without a basis. And it becomes a serious problem when the family complains.
How to deploy frequency detectors in a school
After advising schools in this same situation, this is the protocol we recommend. It has six steps and fits on one page.
- The rule before the device. State in the school regulations that phones, watches and earphones must be off and deposited where the teacher indicates during exams. Add that the school may use radiofrequency detection, and what happens when someone breaks the rule. In state-funded private schools, the change goes through the school council. Moreover, most Spanish regions already restrict phones during the school day: in Madrid, Decree 64/2025.
- Central custody. One or two detectors in the head of studies’ office, with a usage log. Never one in every teacher’s pocket.
- Prior calibration. Sweep the empty classroom to learn the usual signals and adjust sensitivity. The teacher puts their own phone in flight mode.
- Detector mode only. No functions that interfere with, block or intercept communications.
- Verification without records. If the signal persists beside a student, repeat the check. Then ask them to show and hand over the device. Nothing else.
- An incident only with a device. Document the case when the device appears, giving the student and the family a hearing. The academic consequence must be set out beforehand.
With that design, frequency detectors in exams become a necessary, proportionate and defensible measure. Without it, they are just a gadget that beeps.
Three mistakes that turn a good measure into a problem
- Buying a jammer because “it works better”. That is a very serious infringement of the Telecommunications Act.
- Punishing a student because the detector beeped. Without a visible device there is no evidence, and the sanction will not survive a complaint.
- Looking inside the student’s phone. Reaching the content breaches fundamental rights, even when the student is cheating.
Frequently asked questions about frequency detectors in exams
Is it legal to use a jammer during an exam?
No. Act 11/2022 bans holding and using one, apart from exceptions reserved to specific public bodies. A school may not install one, not even during a test.
Do families have to give consent?
No, consent is not required. Exam integrity forms part of the educational function of the school, which has its own legal basis. Families do have to be informed through the school or assessment rules.
May a teacher check the content of a phone?
No. A teacher may ask the student to show and hand over the device, but never reach its content or search personal belongings.
Do they detect a phone that is off or in flight mode?
No. Frequency detectors in exams only pick up devices that are transmitting. That is why depositing the devices before the test remains the main safeguard.
Does the school need a data protection impact assessment?
With a passive detector that records no data, usually not. Even so, write down a short necessity and proportionality assessment. It also helps to consult the school’s data protection officer.
Conclusion
Frequency detectors in exams are lawful and can be useful. The risk does not sit in the device. It sits in using it with no rule, no protocol and a temptation to punish a beep. If your school is considering the purchase, start with the regulations and with a conversation with its data protection officer.
At Auratech Legal we act as external DPO for schools. Moreover, we design measures of this kind so that they work and still respect students’ rights. We analysed a very similar case when we looked at face recognition in exams. We did the same when reviewing cloud privacy in schools and the use of images of minors. If you want your exam protocol reviewed, get in touch with us.
This article provides general information and does not replace legal advice on a specific case.