OCT. 2010 

U.S. Department of Justice 

Office of Justice Programs 

National Institute of Justice 

Toward Criminal JusTiCe soluTions 

IN 

short 

NCJ 231114 

Office of Justice Programs n Innovation • Partnerships • Safer Neighborhoods n www.ojp.usdoj.gov 

10-4 No More? Law Enforcement 

Agencies Are Phasing Out Old 

Radio Codes 

Does “10-13” mean an officer is in trouble or is it a 

request for a wrecker? Is the use of 10-codes hampering your ability to communicate over the radio 

with officers in other departments? 

The use of 10-codes originated in the early 1920s, 

when public safety radio was in its infancy and 

officers rarely had to communicate with officers 

outside their own department. Early radio technology did not provide law enforcement with the 

capabilities that are available today. From the 1920s 

through the early 1980s, most departments used 

one-channel conventional radios to communicate 

with officers in the field. Everyone shared the channel, which became congested when simultaneous 

events took place in different locations. 

Thus, out of need, the 10-codes emerged, although 

they were not standardized. These codes enabled 

departments to pass concise information among 

officers in a minimum amount of radio time, reducing radio traffic. This traffic decrease allowed more 

officers to communicate when they needed to. 

In later years, the use of 10-codes helped to prevent 

suspects who were within earshot from understanding what officers and dispatchers were saying. However, the need to communicate with other 

departments has grown in recent years, and the 

use of 10-codes — which vary across jurisdictions 

— can potentially confuse first responders from 

different agencies when they work together. 

Migrating to Plain language 

Agencies must be able to communicate effectively 

across jurisdictional lines. Using plain language 

helps. The Department of Homeland Security 

encourages plain language in its National Incident 

Management System. How the migration to plain 

language should occur is subject to some debate. 

There are, however, some essential ingredients for 

a successful transition. 

First, law enforcement executives must commit to 

a plan and develop a road map that outlines the 

necessary steps. Executives should first get advice 

from the officers and dispatchers — who will be 

most affected by the change — and then design the 

appropriate training and education programs. 

Second, each agency should be allowed to keep 

a small subset of agency-specific codes that are 

understood by officers but not by the public. For 

example, even agencies that have switched to plain 

language for almost everything else still retain a 

veiled language code that can alert officers to an 

undercover operation. The exceptions to plain language should include a standard word or phrase for 

an officer in trouble. Before the move to plain language, many agencies used some form of the number 13, such as “signal 13” for an officer in trouble. 

Today many agencies have replaced this with a 

brief phrase known only to dispatchers and officers. 

Lastly, some existing plain language can become 

standardized. “Stolen car” may be referred to as 

a GLA (grand larceny auto), a GTA (grand theft 

auto), or some other term in adjacent jurisdictions. However, jurisdictions can agree to adopt a 

standard term. Law enforcement can also adopt 

straightforward words and phrases for situations 

that involve dealing with emotionally disturbed 

people or pursuing fugitives and suspects. 

issues to Consider 

For plain language to be effective, it must be comprehensive and compulsory. Agencies must use it 

for all radio transmissions, not just during mutual 
2 

aid events. Agencies have recognized that some 

codes will still be used during normal radio transmissions, such as 10-4, which is recognized as 

“okay,” “copy” or “acknowledged.” 

Those agencies that have adopted plain language 

have not reprimanded officers who slip and occasionally use codes during this transition. 

Whether or not local agencies choose to switch to 

plain language for everyday use, it is occasionally 

being mandated by some regional and national 

organizations. Most regional communications plans 

put forth by the National Public Safety Planning 

Advisory Committee require agencies that use the 

national calling channels (CAL90, 8TAC91, etc.) to 

use plain language when talking to other agencies on these channels. To avoid mistakes during 

an event, regions should promote the use of plain 

language on a routine basis when using the shared 

channels. Standardized plain language across all 

jurisdictions will remove the confusion that can 

occur when agencies do not use the same codes 

and signals. Law enforcement agencies that routinely use codes and reserve plain language for 

emergencies involving multiple jurisdictions may 

be more likely to lapse into code, even during 

emergencies, which could create confusion. 

Benefits 

Using plain language can help to create clearer 

communication across jurisdictional and agency 

lines. In addition, it may reduce the anxiety experienced by many new officers who have to memorize 

codes. It should also reduce training time for new 

officers. 

Plain language is encouraged by the Department of 

Homeland Security, the Association of Public-Safety 

Communications Officials, and the International 

Association of Chiefs of Police. 

for More inforMation 

n	 NIJ’s Communications Technology 

(CommTech) website: 

http://www.ojp.usdoj.gov/nij/topics/technology/ 

communication/welcome.htm 

n	 NLECTC Communications Technologies 

Center of Excellence: 

http://www.justnet.org/coe_commtech/Pages/ 

home.aspx 

*NCJ~231114*
 

This document is not intended to create, does not create, and may not be relied upon to create any rights, substantive or procedural, enforceable at law by any party in any matter civil or criminal. Opinions or points of view expressed in this document represent 

a consensus of the authors and do not necessarily represent the official position or policies of the U.S. Department of Justice. The 

products and manufacturers discussed in this document are presented for informational purposes only and do not constitute product approval or endorsement by the U.S. Department of Justice.