DNA – The defence approach

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Hand Holding a SubstanceGuest blog post by John Desmond, barrister.

The first item on the agenda for competent criminal defence lawyers faced with DNA evidence that inculpates and appears probative is to do your homework or ‘due diligence”.

A competent lawyer can only do this if he requests all relevant materials from the Crown.

The Crown has continuing obligation of discovery of all relevant documents but if forced, issue a subpoena on VPFSD:

  • The case file. All forms and worksheets that document procedures used to collect, package and label the sample;
  • All records required to demonstrate the chain of custody of the sample/item/evidence;
  • Laboratory records of retrieving the sample, including dates, time sample retrieved and condition of sample, the means by which it was labelled and where it was stored in the lab;
  • Records describing the portion of the item actually used for the analysis and the procedures in place to minimize potential for contamination;
  • Record of the standard operating procedures in place in the lab when it was analysed, covering not only extraction and analysis of the DNA but also the reporting of the data and operation of the relevant instruments and equipment. This includes protocols, records of calibration and preventative maintenance of instruments and results of quality control tests and when same were done;
  • Names of all software programs used to analyse and interpret the data and description of any macros used as well;
  • The raw data from the fragment analyser eg Genescan and Genotyper including injection lists and log files, sample files and project files including templates and macros;
  • Reports of the performance of the standard quality control procedures and any notes made by the analyst during the process;
  • The specific operational parameters programmed into the instrument for that analysis, such as allele size ranges and peak detection thresholds and any macros used to make allele calls;
  • Description of the reference database/s used to calculate the RMP and/or LR including number in the database, the racial and ethnic make up of the population of the database
  • All records as to accreditation of the lab and its personnel, especially proficiency tests taken during period around the subject analysis;
  • Documents certifying the validity of the reference samples used in the analysis such as control DNA samples or the molecular size ladders used to assign alleles;
  • Records as to the reagents used in the analysis were subjected to quality control tests;
  • List of the samples processed immediately before and along with the sample in question;
  • Documents as to any internal audits that included and excluded the subject analysis around the period of the analysis;
  • Catalogue of DNA profiles from technicians, analysts and all who handle and could conceivably contaminate the samples

If the DNA evidence is critical in the Crown’s case then it is up to you to do your homework and get the relevant documents to properly assess if the sample is able to be ruled out or “weakened” in terms of its value.

John’s notable defence work includes high profile murder and sex offences and he approaches his cases with tenacity, uncompromising approach and ardent commitment.

John Desmond, a Victorian Barrister with over 25 year’s experience, is an expert in Criminal Defence Law.

Check out Doogue + George’s LinkedIn profile here.
Date Published: 7 December 2011

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