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Computer evidence

Reliability of computer evidence

1. Evidence pertaining to the reliability of a computer will go to the weight of the evidence produced by the computer. In the absence of any evidence to raise the issue of reliability, the maxim omnia praesumuntur rite esse acta 1 will apply and the computer will be presumed to be functioning properly. 2

As real evidence

2. Where information from a computer was recorded by mechanical means (either where the computer was simply used as a calculator to process information, or the computer was programmed to record information), without passing through a human mind, it constitutes real evidence, i.e. something which speaks for itself. Examples include a printout produced automatically recording details of telephone calls, 3 and the results produced by breathalysing equipment. 4


  1. "All things are presumed to have been done correctly".
  2. S60 Youth Justice and Criminal Evidence Act 1999 repealing s69 Police and Criminal Evidence Act 1984.
  3. R v Spiby [1990] Cr. App. R. 186.
  4. Castle v Cross [1985] 1 All ER 87 AC at 89.
Updated 2009-07-07