Since 2005, drills intended to teach defensive tactics at law enforcement academies have been linked to at least a dozen deaths and hundreds of injuries, some resulting in disability, according to a review by The Associated Press.

The drills — frequently referred to as RedMan training for the brand and color of protective gear worn by participants – are intended to teach law enforcement recruits how to defend themselves against combative suspects. They’re among the most challenging tests at police academies. Law enforcement experts say that when properly designed and supervised, they teach new officers critical skills.

But critics say they can put recruits at risk of physical and mental abuse that runs some promising officers out of the profession. Academies have wide latitude in running such exercises, given a lack of national standards governing police training.

Here are some takeaways from AP’s report.