Advanced

Determining the Base Rate for Guilt

Dahlman, Christian LU (2018) In Law, Probability and Risk 17(1). p.15-28
Abstract (Swedish)
A Bayesian assessment of the probability that the defendant in a criminal trial is guilty depends on the presumed base rate for guilt and the estimated likelihoods of the evidence. This article explores how the base rate shall be determined. Bayesian scholars have recommended a base rate of 1/N, where N is the number of ‘possible perpetrators’, but it is unclear how the reference class of possible perpetrators shall be defined. Several solutions are explored, and it is demonstrated that each solution leads to serious sacrifices in some fundamental principle of criminal justice. Some solutions lead to arbitrary assessments, or assessments that deviate from the facts. Other solutions fail to uphold an acceptable ratio between wrongful... (More)
A Bayesian assessment of the probability that the defendant in a criminal trial is guilty depends on the presumed base rate for guilt and the estimated likelihoods of the evidence. This article explores how the base rate shall be determined. Bayesian scholars have recommended a base rate of 1/N, where N is the number of ‘possible perpetrators’, but it is unclear how the reference class of possible perpetrators shall be defined. Several solutions are explored, and it is demonstrated that each solution leads to serious sacrifices in some fundamental principle of criminal justice. Some solutions lead to arbitrary assessments, or assessments that deviate from the facts. Other solutions fail to uphold an acceptable ratio between wrongful acquittals and wrongful convictions. (Less)
Abstract
A Bayesian assessment of the probability that the defendant in a criminal trial is guilty depends on the presumed base rate for guilt and the estimated likelihoods of the evidence. This article explores how the base rate shall be determined. Bayesian scholars have recommended a base rate of 1/N, where N is the number of ‘possible perpetrators’, but it is unclear how the reference class of possible perpetrators shall be defined. Several solutions are explored, and it is demonstrated that each solution leads to serious sacrifices in some fundamental principle of criminal justice. Some solutions lead to arbitrary assessments, or assessments that deviate from the facts. Other solutions fail to uphold an acceptable ratio between wrongful... (More)
A Bayesian assessment of the probability that the defendant in a criminal trial is guilty depends on the presumed base rate for guilt and the estimated likelihoods of the evidence. This article explores how the base rate shall be determined. Bayesian scholars have recommended a base rate of 1/N, where N is the number of ‘possible perpetrators’, but it is unclear how the reference class of possible perpetrators shall be defined. Several solutions are explored, and it is demonstrated that each solution leads to serious sacrifices in some fundamental principle of criminal justice. Some solutions lead to arbitrary assessments, or assessments that deviate from the facts. Other solutions fail to uphold an acceptable ratio between wrongful acquittals and wrongful convictions. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Law, Jurisprudence, Rättsvetenskap, Allmän rättslära
in
Law, Probability and Risk
volume
17
issue
1
pages
15 - 28
publisher
Oxford University Press
external identifiers
  • scopus:85043454246
ISSN
1470-840X
DOI
doi:10.1093/lpr/mgx009
language
English
LU publication?
yes
id
3ed9c71f-34c7-4402-9ce2-e52ac864d1ac
date added to LUP
2017-12-18 18:00:05
date last changed
2018-03-25 04:41:45
@article{3ed9c71f-34c7-4402-9ce2-e52ac864d1ac,
  abstract     = {A Bayesian assessment of the probability that the defendant in a criminal trial is guilty depends on the presumed base rate for guilt and the estimated likelihoods of the evidence. This article explores how the base rate shall be determined. Bayesian scholars have recommended a base rate of 1/N, where N is the number of ‘possible perpetrators’, but it is unclear how the reference class of possible perpetrators shall be defined. Several solutions are explored, and it is demonstrated that each solution leads to serious sacrifices in some fundamental principle of criminal justice. Some solutions lead to arbitrary assessments, or assessments that deviate from the facts. Other solutions fail to uphold an acceptable ratio between wrongful acquittals and wrongful convictions.},
  author       = {Dahlman, Christian},
  issn         = {1470-840X},
  keyword      = {Law,Jurisprudence,Rättsvetenskap,Allmän rättslära},
  language     = {eng},
  month        = {03},
  number       = {1},
  pages        = {15--28},
  publisher    = {Oxford University Press},
  series       = {Law, Probability and Risk},
  title        = {Determining the Base Rate for Guilt},
  url          = {http://dx.doi.org/doi:10.1093/lpr/mgx009},
  volume       = {17},
  year         = {2018},
}