Murders are spiking. Police should be part of the solution.

Last year, the US’s murder rate spiked by almost 30 percent. So far in 2021, murders are up nearly 10 percent in major cities. The 2020 increase alone is the largest percentage increase ever recorded in America — and a reversal from overall declines in murder rates since the 1990s.

American policymakers now want answers on this surge. One approach has good evidence behind it: the police.

There is solid evidence that more police officers and certain policing strategies reduce crime and violence. In a recent survey of criminal justice experts, a majority said...