Mr Palmer, who was the AFP commissioner from 1994 to 2001, said prosecuting families who have turned to a non-psychoactive form of the drug - such as an alcohol-based tincture of the oil - may not always be in the public interest.

He said while reports of parents giving the illegal drug to their children put police in a difficult position, treating them as criminals “served no good purpose”.

“We exercise discretion all the time and I think this is a classic case where what has to be seriously considered is what public interest is being served,” he said. “They're people trying to deal with an exceptionally difficult situation in the best way they know how."

Mr Palmer’s comments come as a Victorian couple faces possible charges for using cannabis oil to treat their three-year-old son’s severe epilepsy. Cassie Batten and Rhett Wallace were taken into police custody on Thursday after the Epping Sex Offences and Child Abuse Investigation team raided their Mernda home and seized their supplies of the oil.

Ms Batten and Mr Wallace, who have attracted pro bono legal support from former WikiLeaks Party campaign director and barrister Greg Barns, were released but could still face charges of possessing a drug of dependence and introducing a drug of dependence into the body of another.

The raid followed an appearance on Channel Seven’s Sunday Night program in which Ms Batten said her son Cooper’s condition had improved markedly since using the tincture. She said she turned to the cannabis oil because Cooper’s seizures were occurring almost every minute and rendered him unable to walk, talk or see. Within 15 minutes of his first dose, she said Cooper began tracking objects for the first time. He now smiles, laughs and can say “mum” and “dad”.

The family is one of at least 150 throughout the country that are reported to have turned to the oil, which is advertised by its supplier as having so low a dose of tetrahydrocannabinol, the psychoactive in cannabis, that it is not actually illegal.

Medicinal marijuana advocate Lucy Haslam, who is behind a push to legalise marijuana for the terminally ill, said she was “disgusted” with the Batten family’s treatment by police.

Ms Haslam and her former drug squad detective husband have campaigned for marijuana legalisation since seeing its benefits in their son Daniel, who has cancer.

The Haslams’ local police chief and mayor in NSW have publicly backed their campaign.

“I know of suppliers who have been raided and had the tinctures confiscated, but this is the first time that I’ve known of a family,” Ms Haslam said. “You’ve just got to wonder what's prompted it.”

The medical value of the tinctures remains unproven, experts say, due to a lack of research.

President of the Australian Drug Law Reform Foundation Alex Wodak said he was not aware of any study into the use of cannabis to treat childhood epilepsy and that “every obstacle is being put in the way of researchers” wanting to evaluate the possible benefits of using the drug.

Dr Wodak said desperate families should be able to make their case for access to unapproved treatments, which he said could be done via a committee of paediatric neurologists or through the existing special access scheme, which allows terminally ill people to apply for access to unapproved drugs.

“Research is a slow business,” he said. “We don’t have the luxury of just watching these kids and their parents. I would like to see the people making these decisions are not ministers but [are] handed back to experts, the doctors.”