The phrase “10-4, good buddy” has transcended law enforcement to become part of American cultural lexicon, appearing in countless movies, television shows, and everyday conversations. Certain police codes have achieved celebrity status, recognized instantly by millions of Americans who have never worn a badge or worked in emergency services. From the tense “10-33” signaling an officer in distress to the culturally ubiquitous “5150” referencing mental health crises, these codes have become woven into the fabric of popular culture through media representation, true crime documentaries, and daily news coverage.

Police codes gained widespread popularity for practical reasons rooted in radio communication efficiency. In the early days of police radio, bandwidth was extremely limited and transmission quality poor. Officers needed to convey complex information quickly over crackling, unreliable frequencies while keeping radio channels clear for other units. The solution was a system of numeric codes that compressed lengthy phrases into brief transmissions. Instead of saying “I acknowledge your message and will comply,” an officer simply said “10-4.” This brevity proved so effective that police codes proliferated across American law enforcement, though standardization remained elusive.

The popularization of police codes accelerated dramatically with the rise of television police dramas. Shows like “Adam-12,” “Dragnet,” “CHiPs,” and later “COPS” introduced mainstream audiences to the cryptic numeric language of law enforcement. Viewers heard officers casually dropping “10-20” when asking for locations or urgently broadcasting “10-33” during emergencies. Reality TV shows, police scanners available to the public, and social media have further democratized access to these once-insider terms, transforming professional jargon into cultural touchstones.

Understanding the most popular police codes provides insight into both law enforcement operations and American popular culture. These codes represent the intersection of practical communication needs, media influence, and public fascination with the hidden language of those who protect and serve. This comprehensive guide explores the codes that have transcended their professional origins to become recognized—and sometimes misunderstood—by the general public.

The Most Popular 10-Codes in American Law Enforcement

The 10-code system, developed in 1937 by Illinois State Police communications director Charles Hopper, represents the foundation of police radio communication. While hundreds of 10-codes exist, certain codes have achieved universal recognition both within law enforcement and among the general public.

Top 10 Most Recognized Police Codes

10-4: The Most Iconic Police Code

Meaning: Acknowledgment, affirmative, message received and understood

Cultural Impact: Perhaps no police code has achieved greater cultural penetration than “10-4.” This simple acknowledgment has transcended law enforcement to become synonymous with agreement and understanding in mainstream American English. CB radio enthusiasts adopted the term in the 1970s, spreading it to truck drivers nationwide. Movies like “Smokey and the Bandit” popularized the phrase further, making “10-4” recognizable to generations who’ve never operated a police radio.

Proper Usage: Officers use 10-4 to confirm they’ve received and understood instructions from dispatch or other units. It’s a concise alternative to saying “yes,” “I understand,” or “message received.” The code signals comprehension without requiring lengthy verbal confirmation.

Common Misconceptions: Many people incorrectly use “10-4” as a greeting or general affirmation in contexts where it doesn’t apply. In law enforcement, 10-4 specifically acknowledges receipt of information rather than expressing general agreement.

10-20: Location, Location, Location

Meaning: What is your location? / My location is…

Cultural Impact: “What’s your 10-20?” has become shorthand for asking someone’s whereabouts, appearing in countless crime dramas, action movies, and even casual conversation among scanner enthusiasts. The code’s utility in conveying location requests succinctly has made it indispensable in police communications.

Practical Application: Dispatchers constantly need to track officer locations for safety, resource allocation, and emergency response. Instead of asking “Officer Johnson, can you please provide your current location?” a dispatcher simply requests “Unit 7-Adam, what’s your 10-20?” The officer might respond with an intersection, address, or landmark.

Variants: Some departments use variations like “10-21” for “call your station by telephone” or “10-23” for “arrived at scene,” all relating to location and positioning.

10-33: The Ultimate Emergency Code

Meaning: Emergency traffic / Officer needs help immediately

Cultural Impact: While less recognized by the general public than 10-4, the 10-33 code carries enormous weight in law enforcement culture. It’s the verbal equivalent of a panic button, instantly clearing radio channels for life-saving communication.

Critical Nature: When 10-33 is broadcast, all non-emergency radio traffic ceases immediately. Every available unit in the vicinity responds with lights and sirens. The code signals an officer facing imminent danger—active shooting, violent assault, ambush, or other life-threatening circumstances.

Emotional Weight: For officers and dispatchers, hearing 10-33 triggers an immediate adrenaline response. The code represents a colleague in mortal danger requiring instant assistance. Many departments have moved away from 10-codes for routine communication but maintain 10-33 or equivalent emergency signals.

Related Codes:

• 10-99: Officer needs help (less urgent than 10-33)
  
  
• Code 3: Emergency response with lights and sirens activated
  
  
• Code 33: Emergency radio silence (all units cease non-emergency traffic)

10-99: Wanted/Stolen Alert

Meaning: Wanted or stolen person/vehicle/property

Usage Context: When officers run license plates, check identification, or investigate suspicious circumstances, a 10-99 response from dispatch indicates the subject is wanted on warrants or the property is reported stolen. This code triggers heightened officer vigilance and specific tactical approaches.

High-Risk Implications: A 10-99 on a vehicle stop transforms a routine traffic encounter into a potentially dangerous felony stop requiring backup units, tactical positioning, and extreme caution. Officers approach wanted subjects differently, often employing high-risk stop procedures.

Popular Penal, Health, and Vehicle Codes in Public Culture

Beyond the standardized 10-code system, specific legal statute codes have achieved pop culture recognition, particularly those from California whose massive entertainment industry broadcasts these codes globally through film and television.

Code 3: Emergency Response with Lights and Sirens

Meaning: Respond to emergency with lights and sirens activated

Cultural Recognition: Action movies and TV police dramas have immortalized “Code 3” as the ultimate emergency response designation. Audiences worldwide recognize the term as signaling urgent police response to serious crimes in progress or life-threatening situations.

Operational Distinction:

• Code 1: Acknowledge call, respond when convenient (non-emergency)
  
  
• Code 2: Respond immediately without lights/sirens (urgent but not emergency)
  
  
• Code 3: Emergency response with full lights and sirens (imminent danger)
  
  

Legal Implications: Code 3 response authorizes officers to exceed speed limits, proceed through red lights (with caution), and otherwise violate traffic laws when responding to emergencies. However, officers remain liable for accidents caused by reckless driving even during Code 3 responses.

Public Safety: When citizens hear sirens and see flashing lights, they’re witnessing a Code 3 response. Understanding this terminology helps the public recognize the seriousness of police activity and the importance of yielding right-of-way to emergency vehicles.

5150: The Mental Health Code That Became Cultural Shorthand

Meaning: California Welfare and Institutions Code 5150 – Involuntary psychiatric hold for individuals deemed a danger to themselves or others

Extraordinary Cultural Impact: No police code has achieved greater mainstream recognition than “5150.” The term has transcended its clinical origins to become slang for “crazy” or “unstable” in popular culture. Rock band Van Halen titled their 1986 album “5150,” rapper Demi Lovato referenced it, and countless social media posts use the code as shorthand for mental instability.

Legal Definition: Under California law, 5150 authorizes peace officers, mental health professionals, or designated crisis intervention personnel to involuntarily confine individuals experiencing mental health crises for up to 72 hours for psychiatric evaluation if they pose a danger to themselves, others, or are gravely disabled.

Proper Application: Officers encounter 5150 situations during welfare checks, suicide threats, psychotic episodes, and crisis interventions. The code allows emergency mental health intervention while protecting individual rights through time limitations and judicial oversight.

Controversial Usage: Mental health advocates have criticized casual use of “5150” as slang, arguing it stigmatizes mental illness and trivializes serious psychiatric crises. The code represents life-saving intervention, not a punchline.

Related Mental Health Codes:

• 5250: 14-day involuntary psychiatric hold (extension of 5150)
  
  
• 5585.25: 24-hour crisis stabilization hold
  
  

DUI: The Universal Impaired Driving Code

Meaning: Driving Under the Influence (alcohol or drugs)

Universal Recognition: Unlike region-specific codes, “DUI” (and its variant “DWI” – Driving While Intoxicated) enjoys universal recognition across the United States. News coverage of celebrity DUI arrests, high-profile accidents, and public safety campaigns have made these acronyms household terms.

Legal Code Numbers:

• California Vehicle Code 23152: DUI of alcohol or drugs
  
  
• 23153 VC: DUI causing bodily injury
  
  
•  
• Many states: Use their own numbering systems but commonly refer to offenses simply as “DUI”
  
  

Cultural Prevalence: DUI appears constantly in:

• News reports of arrests and accidents
• Public service announcements and awareness campaigns
• Court shows and legal dramas
• Social media discussions of responsibility and consequences
  
  

Severity Spectrum: DUI encompasses first-time misdemeanors with administrative penalties to felonies involving injury or death, repeat offenses, and aggravated circumstances like extremely high blood alcohol content or child endangerment.

Regional Popularity and Departmental Variations

Police codes exhibit fascinating regional variations, with certain codes achieving iconic status in specific geographic areas while remaining unknown elsewhere. The entertainment industry’s concentration in California has disproportionately popularized West Coast terminology.

California Codes in Global Popular Culture

California’s status as the entertainment capital of the world has broadcast its police codes internationally through countless movies and TV shows:

LAPD-Specific Terms:

• Code 4: Situation under control, no assistance needed
  
  
• Code 7: Meal break (officers out of service for food)
  
  
• 187: Murder (Penal Code 187 has appeared in film titles, rap lyrics, and popular culture)
  
  
• 211: Robbery in progress
  
  
• 459: Burglary
  
  

Cultural Examples:

• Snoop Dogg’s “Murder Was the Case (187)” explicitly references PC 187
• Movies routinely feature “211 in progress” for bank robberies
• “Code 4” appears in police procedurals to signal safety
  
  

NYPD Terminology and East Coast Variations

New York City’s equally influential entertainment industry has popularized different terminology:

NYPD-Specific Usage:

• 10-13: Officer needs assistance (NYPD’s equivalent to 10-33)
  
  
• Central: Reference to NYPD dispatch operations
  
  
• Sector Units: Geographic patrol assignments (e.g., “7-Adam”)
  
  
• House: Precinct station house
  
  
• Cultural Impact: Shows like “NYPD Blue,” “Law & Order,” and “Brooklyn Nine-Nine” have introduced millions to NYPD-specific terminology, though these codes remain less universally recognized than California’s statutorily-numbered codes.
  
  

Southern and Midwest Variations

Different regions maintain unique terminology reflecting local law enforcement culture:

Texas Rangers and Southern Departments:

• Heavy use of plain language over numeric codes in many jurisdictions
• “Y’all” and regional dialects influencing radio communication
• Sheriff’s offices using different codes than municipal police
  
  

Midwest Departments:

• Chicago PD’s unique beat system and zone designations
• Greater emphasis on straightforward communication
• Weather-related codes for harsh winter conditions
  
  

Federal Agency Codes

Federal law enforcement agencies including FBI, DEA, ATF, and U.S. Marshals Service often use NATO phonetic alphabet and plain language rather than local 10-codes, though agents working with local departments adapt to regional terminology.

Common Radio Terms and Slang Beyond Numeric Codes

Police radio communication includes numerous verbal conventions and slang terms that have achieved cultural recognition alongside formal codes.

Universal Radio Acknowledgments

“Copy that” / “Copy”

• Meaning: Message received and understood
  
  
• Origin: Military radio communication
  
  
• Usage: More conversational than formal “10-4,” widely used across all emergency services
  
  
• Cultural Penetration: Appears constantly in action films, military dramas, and even casual conversation
  
  

“Roger”

• Meaning: Message received (originally “R” for “received” in radio alphabet)
  
  
• Historical Context: Military aviation terminology adopted by law enforcement
  
  
• Modern Usage: Somewhat antiquated in modern policing, more common in military and aviation contexts
  
  
• Pop Culture: “Roger that” remains popular in movies depicting military or police operations
  
  

“Negative”

• Meaning: No, that is incorrect, or I cannot comply
  
  
• Application: Clear alternative to potentially ambiguous “no” over radio
  
  
• Example: “Dispatch, do you show any warrants for this subject?” “Negative, all clear.”
  
  

“Affirmative”

• Meaning: Yes, that is correct, or I can comply
  
  
• Application: Unambiguous confirmation over radio
  
  
• Professional Tone: Sounds more authoritative than simple “yes”
  
  

Location and Status Terms

“10-97” / “On scene”

• Meaning: Arrived at incident location
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• Importance: Confirms officer arrival, triggers response time tracking, establishes accountability
  
  

“10-98” / “Assignment completed”

• Meaning: Finished with call, returning to service
  
  
• Workflow: Clears officer for next assignment, updates unit availability
•  

“In route” / “En route”

• Meaning: Traveling to assigned location
  
  
• Usage: “Unit 7-Adam, I’m en route to the 211 at Fifth and Main”
•  

“Standby”

• Meaning: Wait for further information, or I’m temporarily unable to respond
  
  
• Application: Officer requests dispatcher pause while conducting activity (traffic stop, foot pursuit, investigation)
  
  

Tactical and Operational Slang

“Hot call”

• Meaning: High-priority emergency requiring immediate response
  
  
• Distinction: Differentiates urgent situations from routine calls
  
  

“Cold call”

• Meaning: Non-emergency situation, often a report taken after the fact
  
  
• Example: Burglary discovered hours after occurrence, no suspects present
  
  

“Code 4 – Safety”

• Meaning: Situation secure, no further assistance needed, all parties safe
  
  
• Relief: Cancels emergency response from other units
  
  

“Cover” / “Cover me”

• Meaning: Request for backup officer to provide safety overwatch
  
  
• Tactical: Second officer positions for safety during high-risk encounters
  
  

“Clear”

• Meaning: Building/area searched and secure, or radio frequency available
  
  
• Multiple contexts: “Building is clear” (no threats found) vs. “Channel is clear” (available for transmission)
  
  

Civilian and Suspect Terminology

“Subject”

• Meaning: Person of interest, suspect, or individual involved in incident
  
  
• Neutral Term: Avoids premature judgment before facts established
  
  

“Complainant” / “RP” (Reporting Party)

• Meaning: Person who called police or reported incident
  
  
• Legal Distinction: Different from victim or witness
  
  

“Suspect”

• Meaning: Person believed to have committed crime
  
  
• Legal Threshold: Reasonable suspicion or probable cause established
  
  

“Perp” (Perpetrator)

• Meaning: Person who committed crime
  
  
• Informal: More common in conversation than formal reports
  
  

The Evolution of Police Code Usage

Modern law enforcement has witnessed significant evolution in code usage, with some departments abandoning traditional systems entirely.

The Plain Language Movement

Following the September 11, 2001 terrorist attacks, the Department of Homeland Security identified communication failures during multi-agency responses. Different agencies using incompatible code systems couldn’t effectively coordinate. This sparked the “plain language” movement encouraging clear, straightforward communication over coded terminology.

Arguments for Plain Language:

• Interoperability: Agencies from different jurisdictions can communicate effectively
  
  
• Public Transparency: Citizens monitoring scanners understand police activity
  
  
• Clarity: Eliminates confusion from regional code variations
  
  
• Training: New officers learn faster without memorizing extensive code lists

Arguments for Maintaining Codes:

• Brevity: Codes convey information faster than full sentences
  
  
• Radio Discipline: Formal codes encourage professional communication
  
  
• Tradition: Codes represent law enforcement culture and identity
  
  
• Tactical Privacy: Some information shouldn’t be broadcast in clear language
  
  

Hybrid Systems

Many departments now employ hybrid approaches, using plain language for routine communication while maintaining critical codes like emergency signals, tactical operations, and sensitive information.

Police Codes in Popular Media and Entertainment

The entertainment industry’s fascination with police codes has created a feedback loop where media representation influences public perception while actual law enforcement communication inspires realistic portrayals.

Iconic Media Moments

Television Shows:

• “Adam-12” (1968-1975): Introduced millions to LAPD codes and procedures
  
  
• “Dragnet”: Made “Just the facts, ma’am” and police professionalism famous
  
  
• “COPS” (1989-present): Reality format broadcasting actual police codes
  
  
• “The Wire”: Showcased Baltimore PD communication and culture
  
  

Movies:

• “End of Watch”: Realistic portrayal of LAPD patrol officer communication
  
  
• “Training Day”: Featured authentic Los Angeles police terminology
  
  
• “Heat”: Bank robbery (“211”) scene using tactical radio communication
  
  

Music:

• Hip-hop culture: Extensively references police codes, particularly California penal codes
  
  
• “187 on an Undercover Cop” – Dr. Dre and Snoop Dogg
•  
• Numerous references to “5-0” (police), “one-time” (police), and statute codes
  
  

Educational Impact

While entertainment often dramatizes or misrepresents police work, code exposure has created unprecedented public awareness of law enforcement communication. Citizens familiar with basic codes can:

• Better understand scanner traffic
  
  
• Recognize emergency situations requiring right-of-way
  
  
• Appreciate the complexity of police coordination
  
  
• Make informed decisions about law enforcement career paths
  
  

Conclusion

The most popular police codes of the United States represent far more than communication shortcuts—they embody the intersection of professional necessity, cultural fascination, and media influence that has made law enforcement terminology part of the American lexicon. From the universally recognized “10-4” to the culturally loaded “5150,” these codes have transcended their operational origins to become cultural touchstones recognized by millions who’ve never keyed a police radio.

Understanding these codes bridges the gap between law enforcement professionals and the communities they serve. When citizens recognize “Code 3” as emergency response or comprehend that “10-33” signals an officer in mortal danger, they develop deeper appreciation for the split-second decisions and coordinated responses that characterize modern policing. This shared vocabulary, popularized through decades of television, film, and news coverage, creates a common language connecting police culture with public consciousness.

As law enforcement continues evolving—some agencies abandoning traditional codes for plain language while others maintain time-honored systems—these popular codes remain embedded in American culture. Whether heard on police scanners, referenced in entertainment, or used colloquially in everyday conversation, these numeric designations and tactical terms represent the enduring legacy of efficient communication born from necessity and elevated to cultural phenomenon.

For those fascinated by law enforcement, understanding these codes opens a window into the professional world of those who protect and serve, while reminding us that behind every code is a human story—officers responding to emergencies, coordinating complex operations, and working tirelessly to maintain public safety in communities across America.