August 30


Prisoner’s Dilemma

The Prisoner's Dilemma is a situation where the two prisoners have to decide whether to cooperate with the police or not. This is studied as part of Game Theory in Economics. 

Would you recommend your client to cooperate or to keep their mouth shut?

Which leads to the best outcome for your client?

Prison cell

The Prisoner's Dilemma is often described as two people arrested for a crime, for example a bank robbery. Each of the suspects is interrogated by the detective. Of course, each prisoner does not know what is happening with the other prisoner - what they are telling the detective or what the detective is telling them. 

So what options does each prisoner have?


Each prisoner could:

  • Keep their mouth shut. Or:
  • Sing like a canary. Spill the beans. In other words, tell the detective everything.

Of course, the other prisoner has the same two options. Remember, they are each being held in a separate interrogation room. They cannot contact or talk to each other during these interrogations.

The detectives have some information against the two prisoners, but cannot prove the bank robbery unless one (or both) of them confess or make some important admissions. In this type of situation, the detectives will try to get one of the suspects to 'flip' against the other: to provide evidence or testimony against their co-defendant. Of course, the suspects do not know exactly what the detectives know or what evidence they have - in fact, the police can mislead or even lie to suspects in this situation. 

So what are the possible outcomes of this situation?

  • If Prisoner A talks, and Prisoner B does not: then Prisoner A walks, and Prisoner B gets 20 years in prison. (Or vice versa: Prisoner B talks and Prisoner A gets 20 years.)
  • If both Prisoner A and Prisoner B talk, then they each get 10 years in prison.
  • If neither Prisoner A nor Prisoner B talk, then they each get 1 year in prison.

This means that both prisoners are better off if neither of them cooperate with the police.

However, if one prisoner does speak, then it is much better for the other prisoner if they speak, too. If they are the only one who does not cooperate, then they will have the worst possible outcome; certainly this would encourage each prisoner to at least consider cooperating.

After all, how much does Prisoner A trust Prisoner B? Or vice versa?


In Game Theory, this is studied in an effort to understand what the optimum outcome would be - for an individual, for a company, or a country. Is it better to cooperate, or go your own way? Or how can you be certain (or even simply encourage) that the other prisoner will not speak? 

What do you think?
What would you recommend to your client in this situation?

Comment below!

For more information about this topic:

Quick explanation of The Prisoner's Dilemma:

But what happens if the 'game' is repeated? Would your strategy change?

Note: Of course, in this scenario - the arrested prisoners are more properly called suspects than prisoners. A prisoner would be someone incarcerated in a prison - which is usually after conviction in court. When people are arrested, they may go to jail, but not directly to prison.  However, since it is called The Prisoner's Dilemma, I have used the term prisoner in this article.


Criminal Law, Law in Practice

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