Smacking unruly schoolchildren with wooden paddles might sound like the stuff of a Roald Dahl novel, but in fact corporal punishment is still permitted in 1 in 2.5 US states.

The US breaks with much of the world on this issue: 106 countries, including most of Europe, Japan, Kenya, South Africa, and New Zealand, have banned the practice. But not the US.

Here, some educators argue that corporal punishment, mostly in the form of “paddling” on the buttocks, is a crucial disciplinary tool. But research shows that it isn’t all that effective. In fact, students who are regularly exposed to physical discipline express more aggression and violent behavior towards their peers and teachers. Nadine Block, Director of the Center for Effective Discipline, says paddling doesn’t work any better than many other disciplinary techniques—and it puts students at risk.

While stinging and minor bruising are the most common outcomes of paddling, some children have sustained more significant damage, including severe bruising and bleeding, blood clots, and muscle damage. In rural east Texas, a ten-year-old was paddled so harshly that his genitals were swollen and bruised.

Aside from the physical harm, opponents of corporal punishment cite the psychological impact as a cause for real concern. Human Rights Watch argues that the use of physical force in schools is degrading to students and damages young people’s self-esteem. Students can feel ashamed and angry, and lose their motivation to learn. The practice may even contribute to kids dropping out of school.

Minority students, boys, and children with special needs are disproportionately paddled: While the odds are 1 in 217.3 that any student will receive corporal punishment in school in a year, the odds are 1 in 104.4 for a black student, and 1 in 142.6 for a male of any race (with black males at highest risk). Black students make up 17.1% of the nation’s schoolchildren, but 35.6% of those getting paddled, and students with disabilities—13.7% of the nationwide school population—make up 18% of those feeling the sting of corporal punishment.

Other disciplinary techniques are also drawing scrutiny.

Many schools nationwide confine students to cell-like seclusion rooms. In some cases, severe trauma has been reported. Isabel Loeffler, an eight-year-old diagnosed with autism, wet herself and pulled her hair out while confined to a storage closet at her school in Iowa. In an extreme and tragic case, Jonathan King, a 13-year-old who had been repeatedly held in seclusion at his Georgia school, hanged himself in the concrete room during one such “time-out.”

In New York City, where corporal punishment is illegal, safety officers employed by the NYPD are stationed in many public schools. These unarmed officers have been known to interrogate, arrest, and handcuff students for such misdemeanors as drawing on desks with erasable markers.

The issue of how schools administer discipline is an important one for the entire community. And parents who feel strongly on either side would do well to investigate individual schools’ practices before enrolling their progeny.