In June, the Carlsbad Police Department posted on the city website an updated policy directive that banned the carotid artery hold, and reshaped the department’s use-of-force policy to conform to a new state law that changed the legal standard for when force can be used.

The policy change was drawn up and formulated not solely by department leaders or city officials. Instead, Carlsbad relied on the work of lawyers at Lexipol, a little-known private company based in Orange County that over the past two decades has quietly become one of the most influential forces in policing across the country.

The company writes policies and provides other services under contracts with thousands of police agencies in 35 states. It claims to have written policies for 95 percent of all police departments in California, most of them small- and medium-sized agencies, like Carlsbad.