There are cellphone bans in schools around the world. Do any of them work?

From magnetic locking pouches and blocked Wi-Fi access to outright bans and legislation, schools around the world have been waging war on cellphone use for years.

In Canada, too, several provinces have introduced cellphone bans for the 2024-25 school year. The bans vary by jurisdiction, but they all have a similar aim: to restrict cellphone use in classrooms to cut down on distractions and encourage safe social media use.

But as the bans gain global momentum — along with confusion about how they will be enforced and criticism about lack of consistency — some researchers say there isn't enough evidence on whether they're actually effective.

"Politicians seem to say, as a very easy, nice slogan, 'Ban the phones. Stop the phones.' It's catchy," said Marilyn Campbell, a professor in the School of Early Childhood and Inclusive Education at the Queensland University of Technology in Australia who studies cellphone bans in schools.

But there's very little actual research on whether prohibiting cellphones improves certain parameters, such as cyberbullying rates, student mental health, distraction and academic performance, Campbell told CBC News. And even when there is good research, the evidence is conflicting, she said.

"We don't know that it's beneficial, and we don't know that it's detrimental. We don't have enough research to say one or the other," Campbell said. "My position is that, as we don't know, why does government insist all schools ban them?"

Across the globe, particularly in the past two years or so, different jurisdictions have announced all different kinds of cellphone bans in the classroom, said Sachin Maharaj, an assistant professor of educational leadership, policy and program evaluation at the University of Ottawa who also studies school cellphone bans.

The impacts haven't been studied vigorously in most places until very recently, he said in an interview. While the schools that ban phones tend to show improved academic outcomes in those few studies, it's not uniform, Maharaj said.

"The academic benefits tend to confer most among those students who were the lowest achieving, which sort of makes sense because probably the students who were the most distracted by phones were the ones who were doing worse in school," he said.

There are cellphone bans in countries around the world, most of them implemented regionally. The list of countries with bans and regions within them is constantly growing and changing. For instance, over the summer, Cyprus and the Netherlands announced a ban in schools, as did several Canadian provinces and a handful of U.S. states and districts.

In 2023, UNESCO called for schools around the world to ban cellphone use in classrooms. The United Nations education agency cited research linking their use with distraction and poorer academic performance. At the time, it noted that about one in four countries across the globe banned cellphones in classrooms and that bans are more common in Asia.

It also suggested that in schools where cellphones are prohibited, students are significantly less likely to be distracted during lessons.

Some of the countries with bans include France, which has blocked cellphones in classrooms since 2018; Italy, where an original ban was announced in 2007 and extended last winter; Spain, where the types of bans vary by region; and Australia, where cellphones are prohibited in all state schools, but how the ban is enforced varies by state, territory and grade.

In 2021, children in China were banned from bringing cellphones to school without written parental consent. In Cyprus, the new ban will stop students from turning their phones on but not from bringing them to school. The new Dutch ban, like many others, leaves schools to come up with their own plans to enforce the rules.