Yet even where guns are routinely carried, use of them is far rarer in Europe and some other English-speaking countries than in the US. Many experts link that partly to education and pay, which have turned policing into a well-respected career with prestige and perks. In the US, police training lasts on average 19 weeks. In much of Europe that would be unthinkable, says Mr. Kersten. German police, for example, train for at least 130 weeks.

In fact, since 2008 in North Rhine-Westphalia, becoming a police officer means a stint at a university, sitting in law classes, learning about the cultural customs of Muslims, and debating ethics. 

Outside the classroom, during training activities such as target practice, recruits are surrounded by messages urging prudence. “Super shooting, I hope you never need it in real life,” reads one poster at the facility in Selm. Another lists the number of times police fired their guns each year up to 2010. In that year, there were 9,450 shootings. Of those, 9,342 involved animals.

The lengthy training regimen in Germany doesn’t seem to discourage people from wanting to become cops, either. Some 8,000 candidates competed to join North Rhine-Westphalia’s 40,000-strong force. Only 1,640 spots were available.