What are some explanations of the chain of custody: how is it used in court, and what is its purpose?

Chain of custody refers to official documentation of the
complete sequence of activities connected with collection, custody, transfer,
examination, and deposition of evidence used in legal
proceedings.

The evidence can be a physical evidence such
as drugs seized from a person, or a weapon used in a crime. It can also be some evidence
in electronic or other forms such as video recording or some storage medium in
computer.

The chain of custody must include detailed
information on persons collecting and handling the evidence, timing of various actions
by such persons, conditions under which the actions took place, and the precautions
taken to prevent tempering with the evidence.

The purpose
of chain of custody of evidence is to ensure and provide a proof that no unauthorised
access or tampering with the evidence took place. Without such back up of chain of
custody, no evidence is valid in a court of law.

For
example if a glass tumbler containing fingerprints of a person obtained from the scene
of crime is presented as evidence then the chain of custody will record details such
as.

• Description of the
  evidence.


• How obtained the evidence, from where and
  when.


• When it was handed over to forensic lab for
  examination, and the identity of person receiving
  it.


• Nature and timing of analysis performed on
  it.


• Details of handover of evidence to the evidence
  clerk.


• Details of the place of storage by the evidence
  clerk.


• Details of any other persons accessing and
  examining the evidence while it is in the custody of the evidence
  clerk.