• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
  • Skip to footer
  • Home
  • About
  • The Magazine
  • Events
  • Partners
  • Products
  • Contact
  • Jobs and Careers
  • Advertise
  • Facebook
  • Instagram
  • Twitter
  • Subscribe
American Police Beat

American Police Beat Magazine

Law Enforcement Publication

  • Home
  • Leadership
    • Smart power
      Can your staff keep pace with your leadership goals?
      Your agency needs you
      Pursuit termination option: Radiator disablement
      Liability — not always a showstopper!
  • Topics
    • Leadership
      • Smart power
        Can your staff keep pace with your leadership goals?
        Your agency needs you
        Pursuit termination option: Radiator disablement
        Liability — not always a showstopper!
    • Editor’s Picks
      • Mental health checks … in the training room?
        Crime doesn’t take a vacation
        The power of mediation
        Therapy isn’t just for the broken
        Police humor only a cop would understand
    • On the Job
      • The power of calm-edy
        Domestic violence
        Code Red, all hands on deck
        Texas manhunt captures suspect in shooting of officer and K-9
        “Wanna hop in?” Louisiana officer gets a lift from a good...
    • Labor
      • When you are falsely accused
        Is anyone listening?
        The power of mediation
        Differentiation in police recruitment
        Building positive media relations
    • Tech
      • Gear that moves with you
        A new breed of cop car
        The future of patrol is here
        New York governor highlights $24 million investment to modernize law...
        Cutting-edge police technology
    • Training
      • Effective in-service training
        The untrained trainer
        The vision behind precision
        Mentorship: Ensuring future success
        Unlocking innovation
    • Policy
      • New Mexico’s Law Enforcement Retention Fund keeps experienced,...
        The phenomenon of trauma bonding in law enforcement
        Betrayed from within
        Supreme Court declines to revive Missouri gun law
        Quotas come to the end of the road
    • Health/Wellness
      • Maintain your mental armor
        Beyond crisis response
        Mental health checks … in the training room?
        Surviving and thriving in retirement
        Fit for duty, fit for life
    • Community
      • Community engagement: What is it moving forward?
        Contradictory crossroads
        Back-to-school season brings out police support nationwide
        A bold idea for reducing homelessness in America
        Operation Brain Freeze keeps community cool
    • Offbeat
      • An unexpected burglar
        Police humor only a cop would understand
        Not eggzactly a perfect heist
        Pizza … with a side of alligator?
        Wisconsin man charged with impersonating Border Patrol agent twice in...
    • We Remember
      • A Christmas loss
        York County ambush leaves three officers dead, others critically...
        Honoring the Fallen Heroes of 9/11
        Team Romeo
        National Police Week 2025
    • HOT Mail
      • The War on Cops Continues Unabated
  • On the Job
    • The power of calm-edy
      Domestic violence
      Code Red, all hands on deck
      Texas manhunt captures suspect in shooting of officer and K-9
      “Wanna hop in?” Louisiana officer gets a lift from a good...
  • Labor
    • When you are falsely accused
      Is anyone listening?
      The power of mediation
      Differentiation in police recruitment
      Building positive media relations
  • Tech
    • Gear that moves with you
      A new breed of cop car
      The future of patrol is here
      New York governor highlights $24 million investment to modernize law...
      Cutting-edge police technology
  • Training
    • Effective in-service training
      The untrained trainer
      The vision behind precision
      Mentorship: Ensuring future success
      Unlocking innovation
  • Policy
    • New Mexico’s Law Enforcement Retention Fund keeps experienced,...
      The phenomenon of trauma bonding in law enforcement
      Betrayed from within
      Supreme Court declines to revive Missouri gun law
      Quotas come to the end of the road
  • Health/Wellness
    • Maintain your mental armor
      Beyond crisis response
      Mental health checks … in the training room?
      Surviving and thriving in retirement
      Fit for duty, fit for life
  • Community
    • Community engagement: What is it moving forward?
      Contradictory crossroads
      Back-to-school season brings out police support nationwide
      A bold idea for reducing homelessness in America
      Operation Brain Freeze keeps community cool
  • Offbeat
    • An unexpected burglar
      Police humor only a cop would understand
      Not eggzactly a perfect heist
      Pizza … with a side of alligator?
      Wisconsin man charged with impersonating Border Patrol agent twice in...
  • We Remember
    • A Christmas loss
      York County ambush leaves three officers dead, others critically...
      Honoring the Fallen Heroes of 9/11
      Team Romeo
      National Police Week 2025
  • HOT Mail
    • The War on Cops Continues Unabated
  • About
  • The Magazine
  • Events
  • Partners
  • Products
  • Contact
  • Jobs and Careers
  • Advertise
  • Subscribe
Search

Training

An equation for performing lawful Terry stops

Don McCrea Published June 24, 2022 @ 6:00 am PDT

iStock.com/kali9

My school day began like any other. My mother pulled up outside Lamberton Elementary in our Chevrolet Bel Air station wagon and, with a sigh of relief, deposited me and my two brothers outside the east gate. As we jostled with each other on our way to the entrance, I felt an ominous storm cloud hanging over our school.

It was many years later when I learned that storm cloud originated in 1958, when President Eisenhower signed into law the National Defense Education Act — an act that increased federal spending for public schools. Included in this act was something called the “New Math,” a veritable storm cloud unleashed nationwide upon innocent and unsuspecting grade-schoolers like myself. Some parents and educators weren’t too keen on the New Math, either. In fact, Morris Kline, longtime professor of mathematics at New York University, authored a book titled Why Johnny Can’t Add: The Failure of the New Math.

The New Math is remembered as a “dismal mistake,” and has been called “one of the worst ideas of the 20th century.” We weren’t even allowed to use the word “numbers.” Instead, we had to use the word “numerals.” Are you kidding me? When you’re only 6 years old, the word numeral isn’t even a thing.

It’s necessary that officers make lawful stops every time. In doing so, the constitutional rights of citizens are maintained, and the chances of an officer committing a civil rights violation can be significantly reduced.

So if you’re wondering how a kid who grew up under the New Math would eventually develop an equation for performing lawful Terry stops, keep reading!

In my last article for American Police Beat, I identified six reasons officers perform unlawful stops and detentions. Without articulable and particularized reasonable suspicion of crime that has, is or is about to occur, an officer may not:

  • Detain based on a hunch, gut feeling or to conduct a “fishing expedition”
  • Detain because “we got a call for service” or “people are calling us about you”
  • Detain based on mere suspicion alone
  • Detain to see if there is a reason to detain
  • Detain because someone didn’t like what someone else was doing
  • Detain due to a “happenstance of geography”

Unlike a stop based on probable cause (where a violation is observed prior to the stop), a stop based on reasonable suspicion of crime occurs without observing a violation first.

Since unlawful Terry stops can lead to numerous lawsuits and other serious consequences against officers and their agencies, the importance of proper decision-making and articulation under the totality of the circumstances cannot be overstated. Therefore, I’m sharing an equation I developed to assist officers with their Terry stop decision-making and articulation.

That equation is C + R + C = a lawful Terry stop.

The first “C” in the equation represents “crime.” An officer must articulate a particular crime or crimes from the information they receive. Do not perform or attempt a Terry stop based upon any of the six reasons previously listed, as there is no specific, articulable reasonable suspicion of crime associated with any of them.

The “R” in the equation represents “reliability.” There are three primary sources of reasonable suspicion. Those three sources are (1) an officer himself or herself, (2) other officers and (3) citizens. Officers are automatically deemed reliable, and may pass reasonable suspicion to stop and detain to other officers under the collective knowledge doctrine.

Under the citizen–informant doctrine, citizens who are victims or eyewitnesses to crime are a presumptively reliable source of information in one of two ways. If a citizen reports potential criminal activity into a 9-1-1 call center, even anonymously, they are deemed reliable. If a citizen reports potential crime through means other than 9-1-1, they are deemed reliable if they provide their contact information or are otherwise identifiable.

The second “C” in the equation represents “corroboration.” This element involves corroboration of the vehicle and/or suspect description. Corroborating all descriptive points isn’t necessary under Terry, but the more points an officer corroborates, the stronger their case for the legality of the stop under the totality of the circumstances.

For example, how many possible points of corroboration are contained in the following vehicle description: a blue Chevrolet Impala, South Dakota license 675 PRW being driven by an elderly white male?

If you counted 13, you are correct. Isn’t math great?!

An interesting sidenote regarding corroboration. Some officers still operate under the mistaken belief that to perform a lawful Terry stop they need to corroborate or witness the reported crime instead of corroborating the vehicle or suspect description. In essence, these officers won’t make a stop unless they have probable cause instead of reasonable suspicion. This mistaken belief seems most prevalent when officers respond to reports involving a driving or traffic complaint, which can place the traveling public at unnecessary risk.

Here’s a scenario to illustrate how to apply C + R + C = a lawful Terry stop:

An officer receives this report from dispatch: “I have an RP on 9-1-1 reporting that she just observed someone enter her car in the Walmart parking lot and steal her purse from inside. The suspect then drove away in a green Chevrolet Caprice, South Dakota license 634, balance unknown. Suspect is described as a white male, approximately 20 years of age, wearing a blue T-shirt and blue jeans. RP last saw the vehicle leaving the east exit of the store and heading north on Industrial Drive.”

Ten minutes later, the officer spots a green Chevrolet Caprice traveling east on 27th Street. The license plate is South Dakota 634 090, but she couldn’t see who was driving the car. Since the officer never observed the reported violation, does she have the lawful authority to stop this vehicle immediately based on reasonable suspicion of crime provided by the citizen caller?

Let’s use the equation C + R + C = a lawful Terry stop to assist us in determining the answer to that question!

C = Crime. From the information provided by a citizen via dispatch, the officer could reasonably determine that criminal entry into a motor vehicle, or a vehicular burglary, had occurred. This satisfies the first part of the equation.

R = Reliability. Since the citizen reported the potential crime to 9-1-1, the citizen is deemed reliable. This satisfies the second part of the equation.

C = Corroboration. The officer corroborated the vehicle make, model, color, license plate state and the first three positions of the license plate. This sufficiently satisfies the third and final part of the equation.

Thus, the elements of C + R + C were met, and a lawful Terry stop could be performed.

C + R + C also provides a great template for an officer to articulate the legality of their stop in a written report as well as courtroom testimony.

C + R + C can be successfully applied to all types of potential crime, including traffic complaints. Ultimately, when a call goes out, an officer must make a decision whether to stop or not stop. It is my desire that providing this equation will aid officers in their Terry stop decision-making and articulation.

It’s necessary that officers make lawful stops every time. In doing so, the constitutional rights of citizens are maintained, and the chances of an officer committing a civil rights violation can be significantly reduced.

Don McCrea

Don McCrea

Don McCrea is president of Premier Police Training and has 35 years of law enforcement experience. He is a subject-matter expert in non-escalation, de-escalation, search and seizure, and use of force. Don is a nationally and internationally certified instructor and has an IADLEST nationally certified course, “Confident Non-Escalation: This Is Where De-Escalation Training Begins.” He currently serves as academic program coordinator for a four-year law enforcement degree program and offers consulting and training services for law enforcement agencies, the U.S. DOJ, COPS Office and CRI-TAC.

View articles by Don McCrea

As seen in the June 2022 issue of American Police Beat magazine.
Don’t miss out on another issue today! Click below:

SUBSCRIBE TODAY!

Categories: Training

Primary Sidebar

Recent Articles

  • Effective in-service training
  • National Law Enforcement Officers Memorial Fund Announces November 2025 Officers of the Month
  • When you are falsely accused
  • The untrained trainer
  • Maintain your mental armor
  • Smart power
  • The power of calm-edy
  • Can your staff keep pace with your leadership goals?
  • New Mexico’s Law Enforcement Retention Fund keeps experienced, certified officers in state
  • Domestic violence

Footer

Our Mission
To serve as a trusted voice of the nation’s law enforcement community, providing informative, entertaining and inspiring content on interesting and engaging topics affecting peace officers today.

Contact us: info@apbweb.com | (800) 234-0056.

  • Facebook
  • Instagram
  • Twitter

Categories

  • Editor’s Picks
  • On the Job
  • Labor
  • Tech
  • Training
  • Policy
  • Health/Wellness
  • Community
  • Offbeat
  • We Remember
  • Jobs and Careers
  • Events

Editor’s Picks

Mental health checks … in the training room?

Mental health checks … in the training room?

November 25, 2025

Crime doesn’t take a vacation

Crime doesn’t take a vacation

November 21, 2025

The power of mediation

The power of mediation

November 20, 2025

Therapy isn’t just for the broken

Therapy isn’t just for the broken

November 14, 2025

Policies | Consent Preferences | Copyright © 2026 APB Media, LLC | Website design, development and maintenance by 911MEDIA

Open

Subscribe

Close

Receive the latest news and updates from American Police Beat directly to your inbox!

  • This field is for validation purposes and should be left unchanged.