Criminals on juries

The Dom Post reports:

Two people with drug convictions who sat on a jury in a High Court drug trial tried to skewer the case, speaking of police as “pigs” and claiming the evidence was made up, another juror says.

The Wellington woman who sat on the jury with them is adamant jury vetting should be allowed. It took other jurors hours to bring them around.

The woman said she despaired at the justice system after the experience. She welcomed a Supreme Court decision issued yesterday that defended the practice of “jury vetting” the practice of police revealing potential jurors’ criminal convictions to lawyers and said that in her opinion the practice was absolutely crucial.

I would go beyond vetting. I can’t work out why you would possibly have convicted criminals sit on juries.  At the moment the prohibition is only:

Anyone sentenced to a prison term of more than three years, or to more than three months in the past five years, is prohibited from sitting on a jury.

How about anyone who has ever been sentenced to a prison term is prohibited and anyone who has been convicted of any offence within the past five years is also prohibited?