A Perth woman has won a landmark appeal against a court order for her to provide DNA in a paternity dispute after it was ruled submitting a mouth swab against her will could be an assault.
The unanimous decision by three Court of Appeal judges set aside a Supreme Court order and is one of the first to support a person's right to refuse DNA testing in non-criminal cases.
It adds weight to the argument such testing could be an assault.
The woman, 61, was ordered to have DNA testing last year after a woman claimed to be her younger half-sister from an affair her mother had with the other woman's father in Austria in 1960.
The man died in 2008 and the second woman, 52, sought a share of his estate as his daughter.
The older woman rejected the claim and a request for her DNA but Supreme Court Master Craig Sanderson ordered the mouth swab for "kinship analysis".
In his appeal decision last week, Justice Christopher Pullin found courts could not order the woman to consent to what would otherwise be an assault.
He said WA's Criminal Code stated a person who touched or applied force of any kind to another person without their consent was said to assault that person.
The woman did not consent to the swab, so any force applied by the doctor while taking it would be a criminal assault.
Justice Graeme Murphy said ordering someone to submit to a DNA test in a civil case failed to recognise "bodily integrity".
He said to allow interference with someone's property rights or grant access to a premises for limited purposes was not the same as allowing "interference with their person".
Lavan Legal solicitor Courtney Robertson, for the woman who fought the DNA order, said it was important because it reversed the only recent ruling on such a case and found courts did not have an inherent power to order DNA tests for civil proceedings.