Considerations for Selecting a Laboratory for DNA Testing

There are many issues that may need to be considered when selecting a laboratory to perform DNA testing in connection with a postconviction proceeding. Some of these issues are outlined below:

What DNA tests are available in the laboratory?

The DNA tests available in a laboratory need to be considered when selecting a laboratory for testing postconviction relief samples. Several questions that should be addressed are:

What is the size and type of the sample?

The size and type of the sample will determine which DNA tests can be performed. Samples available for testing are often quite small and may not have been properly stored, which may have caused the degradation (breaking down) of the DNA. Either of these situations will make the samples unsuitable for RFLP testing; therefore, the selected laboratory must have PCR testing capabilities. If the DNA is severely degraded, or the sample to be tested is a hair shaft or dried bone, PCR testing of nuclear DNA may not yield results, and a laboratory that performs mitochondrial DNA testing should be considered.

What is the level of discrimination required in the testing?

If the desired testing outcome is to simply distinguish one known individual from another known individual (e.g., the consensual partner from the perpetrator in a sexual assault case), then the discriminatory capabilities of the test methods available in the laboratory may not matter. However, if the test must be highly discriminatory so as to eliminate falsely accused individuals, particularly if any individuals are related, then the discrimination capabilities of the tests available in the laboratory should be considered. A laboratory should be selected that has the testing capabilities to address the level of discrimination required.

Have samples been tested previously that will be used for comparison purposes?

If the samples to be tested will be compared with results from samples tested previously (e.g., known individuals in convicted offender databases, samples from other possible serial sexual assault cases, results from samples tested in the laboratory selected by opposing counsel), then the selected testing laboratory must have the appropriate tests available so that the data may be compared.

Will the test results be compared to those in a DNA database?

If the defendant is found to be innocent of a crime for which he or she was convicted based on being excluded as the donor of the DNA from a relevant sample, then the prosecutor may want to compare the DNA test results to those in databases of convicted offenders (e.g., CODIS) to help identify the true perpetrator. In this situation, it will be important to use DNA tests compatible with the database to be used for comparison purposes.

What experience does the laboratory have?

A laboratory should be selected that has experience using the particular DNA test method to be used on the type(s) of forensic samples that will be analyzed in the postconviction relief case. Information regarding validation studies performed by the laboratory and its history of obtaining reliable results on samples similar to those being tested in the postconviction case with that test method may be requested.

Is there an expert(s) available for consultation and testimony?

The experience and availability of experts from the laboratory to assist the attorneys and the court in decisions regarding the appropriate samples to be tested, the test methods to be used, the meaning of the results, chain-of-custody issues, and the need for testing additional samples from other individuals should be considered. It may also be important to consider the qualifications of the expert(s) and his or her experience in presentation of DNA data to the court.

Is the laboratory accredited?

Accreditation is a process in which a laboratory undergoes a review and onsite inspection by individuals from other DNA testing laboratories. This process generally requires a review of the procedures followed in the laboratory for DNA testing, security, evidence handling, protocol validation, and documentation of results, proficiency testing, and quality assurance to determine if they meet accepted guidelines. The laboratory is accredited if it meets the specified criteria for accreditation. Other review processes include certification and internal and external audits of the laboratory.

Does the laboratory do testing for the prosecution or the defense?

It may be important to consider the laboratory's policies regarding those for whom it does testing. Some laboratories may only be available for testing by the State or by the defense. Some laboratories may be retained by either the defense or the prosecution but may not be able to work for both parties jointly; for instance, a particular laboratory's policy may preclude a prosecutor and defense counsel from agreeing to share decisions about testing and to both receive test results. The perceptions of bias in the testing laboratory may also require consideration.

What level of confidentiality does the laboratory maintain?

The laboratory's policies regarding confidentiality and discovery may need to be considered. Although it is recommended that all results from postconviction relief testing be available to the prosecution, the defense, and the court, there may be circumstances in which the results of the testing must remain confidential. It may also be important to understand if the test results from a particular postconviction case will be usable in other ongoing investigations of unsolved cases. For example, will the defendant's DNA profile be entered into any laboratory or State database for future comparison purposes?

Is the laboratory a public or private laboratory?

This may be an important consideration for determining whether the laboratory can be retained by either the prosecuting or defense attorney or both. It may also affect whether the counsel who did not request the DNA tests has access to the laboratory's experts for consultation, the availability of expert testimony and discovery, the cost of testing, and confidentiality issues.

What materials are available from the laboratory for discovery purposes?

At times, an attorney, an expert, or the court may request documentation of the DNA tests performed in a postconviction case, or information about quality control/assurance, chain of custody, validation studies, proficiency tests, and/or information regarding the databases used. It may be important to consider what materials are available from a laboratory before doing the DNA testing if this could become an issue in a particular case.

What is the laboratory's policy for retaining untested portions of samples and/or DNA extracted from a sample?

Samples tested in connection with postconviction requests are often quite old and small, particularly if RFLP testing had been attempted previously. There may only be a sufficient sample to do a limited number of tests. In this situation, it is important to understand the laboratory's policy regarding destruction of the entire piece of evidence versus retention of a portion of the untested sample as well as a portion of the extracted DNA for possible future testing. The laboratory should test only the amount of sample needed to obtain reliable results and should retain any untested sample and/or extracted DNA whenever possible so that repeat or additional testing can be performed at a later time. (See Retention of Samples for Future Testing for further discussion.)

Does the laboratory permit outside experts to observe testing?

Samples tested in postconviction relief cases are often limited in size (e.g., a single hair root or a very small bloodstain) and cannot be divided prior to isolating the DNA from the sample. Since the sample will be destroyed during DNA testing, if there is only enough sample for one test, the attorney who did not select the testing laboratory may request that an expert be permitted to observe the DNA testing. Some States have statutes or case law permitting a defendant the right to have the testing witnessed when evidence will be consumed (e.g., Colorado, California). In these situations, it will be important to select a laboratory that permits outside experts to observe the testing and to understand its policies concerning outside expert witnesses.

Has the laboratory done previous testing in this case?

For continuity in testing or for consideration of potential bias, it may be important to consider whether the laboratory has already been involved in testing for the case.

Go to the Next Section: Selection of Samples for Testing

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