WA man has indefinite jail term overturned

Kingsley Pickett was 14 when he caused a crash that killed a woman and her one-year-old son

A Perth man who raped a woman during a home invasion and already had an "atrocious" juvenile record, including killing a pregnant mother and her baby in a high-speed crash, has had his indefinite jail term quashed.

Kingsley Arnold Pickett was aged 14 when he caused the crash that killed Margaret Blurton and her one-year-old son Shane on Boxing Day in 1991.

In 2000, Pickett was jailed for the November 1998 home invasion and at the time was already serving a sentence for unrelated offences, so the additional term was ordered to be served partly cumulatively.

The judge also made an indefinite imprisonment order, but Pickett took his case to the West Australian Court of Appeal, successfully arguing that the judge erred by "applying the wrong test" when making the order.

"In the absence of expert psychiatric or psychological evidence, offences committed at the age of 21 years or less ... provided an insufficient foundation to conclude, on the balance of probabilities, that when released from prison aged almost 30 years the appellant would be such a danger to society ... as to reasonably justify the making of an indefinite imprisonment order," the judges said.

Pickett, now aged 41, was re-sentenced to a total effective sentence of 14 years and seven months in prison, and the indefinite detention order was scrapped.

He remains behind bars pending a decision on whether he should be deemed a dangerous sex offender, which would still keep him locked up indefinitely.