Can DNA evidence be excluded from court?

Yes.

DNA evidence can be excluded from court before the jury hears it.

Courts consider not only whether DNA evidence is relevant, but whether it is sufficiently reliable and whether its probative value outweighs any risk of unfair prejudice. Where concerns arise about how the evidence was generated, interpreted, or presented, applications may be made to limit or exclude it.

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In some Australian jurisdictions, for example, section 137 of the Evidence Act allows a court to refuse to admit prosecution evidence where its probative value is outweighed by the danger of unfair prejudice to the accused. This provision may be relied upon in matters involving DNA evidence where the findings are weak, complex, overstated, or at risk of being misunderstood by a jury.

Issues that may affect admissibility include how samples were collected, continuity and handling of exhibits, contamination risks, sampling strategies, interpretation of mixed or low-level DNA, and the statistical methods used to express findings.

DNA evidence may also be challenged where conclusions are overstated, where assumptions underpinning analysis are unclear, or where the results do not properly address transfer, persistence, or alternative explanations.

An application to exclude DNA evidence is both legal and inherently scientific.