(Bad Cop standing over suspect): “Look, we know your friend ran off with the cash, and you helped him. Let’s make this real simple: WHERE IS HE?”

(Suspect, calmly): “I don’t know where he is.”

(Bad Cop): “You know I could throw on an impeding an investigation charge — another 5 years!? One last time: WHERE IS HE?”

(Suspect): “I’m not saying anything.”

(Bad Cop): “You fucked up. I’m not sure I can help you after this. I’m going to get the paperwork for the next charge.” (bad cop leaves)

(Minutes later Good cop quietly enters the room with a root beer): “Hey, want to share a root beer?”

(Suspect): “You pigs are idiots.” (takes root beer)

(Good cop, sits down): “I’m sorry, he can get pretty worked up about things. While you were talking, I read through your file. This isn’t the first time your friend took off and left you the bill is it?”

(Suspect): “You don’t know the half of it.”

(Good cop): “You might be surprised. Have any idea how often I have to finish my partner’s paperwork? Did you see that vein coming out on his forehead? You know, after he left here, he went outside and punched the soda machine? What a hothead.”

(Suspect): “My friend can’t control his temper either. Gets both of us in tight spots all the time and I have to bail him out.”

(Good cop): “My boss said I’ve got no choice but to work with mine. What’s your excuse?”

(Suspect): “I needed the money to pay my family’s mortgage.”

(Good cop): “Oh I remember your kids now, I’ve got a 3-year-old too — man, they’re cute. Don’t you live in the neighborhood? You know there’s a program to get assistance.”

(Suspect): “No I didn’t.”

(Good cop): “I’ll get you the paperwork for the program. What’s your friend going to do with the money with you stuck in here?”

(Suspect): “Drugs.”

(Good cop): “I bet that’s not going to help your family. I tell you what, I can probably get my partner to wave the charge, and we’ll get you back home with the paperwork this evening if we can get the money back.”

(Suspect): “Ok….”

The classic good cop, bad cop routine was described as “one of the oldest devices in police work,” in a book from 1940 on Police Interrogation.

This was just an example. But what you can see is the setup for phase change as our Gibbs energy equation describes. Remember that G2-G1 is indicative of change where

G = U + PV – TS

In good cop, bad cop, the bad cop focuses on ratcheting up the stress (P), flustering an individual with values (U), and depriving them of others, resources, or connection. The good cop comes in later with a simple focus (low U), calm demeanor (low P), and offerings of resources or connections (high T and S). Classic negative change of G2-G1.

The Good Cop, Bad Cop routine has found its way outside of criminal justice. It’s a common analogy to describe the relationship between a university president (good cop) and provost (bad cop). CEOs and CFOs likely evolve a similar duality. Probably even parents.

It turns out that our social thermodynamics simply explains one of the oldest tricks in the book. Maybe it will help our officers know when and how to apply it with a little more efficiency.

(Note: this post is one chapter of what could become a book someday. The other chapters can be found here: https://hydrogen.wsu.edu/dr-jacob-leachman/ )