5 10 Codes: Historical Context

“10-4!”

Different versions of “10 Codes” are used by law enforcement agencies and security professionals across North America. The idea of a common code for law enforcement purposes was first proposed by the Association of Public Safety Communications Officials (APCO) in 1935. This proposal was part of a broader call for a shared communications strategy. APCO’s “10 Codes” list was developed from 1937-1940. Like all languages,  the specific meaning of the individual codes evolved over time. The result is that some codes, such as “10-4,” have a consistent meaning that many civilians recognize from movies and tv shows. Other codes, however, might have unique meanings from one agency to the next.

While the original intention of APCO’s proposal was to unify different agencies, many law enforcement agencies today keep their specific “10 Codes” confidential. They do this to protect the privacy of their communications in the interest of public safety. This means that there is no longer a single, universal version that is shared by all law enforcement communities.  The codes that appear in this exercise, however, are relatively common. They are based on those used by the Ontario Provincial Police and APCO Project 14.