Prosecutors have conceded the first conviction under Australia's toughest anti-bikie laws relied on an inadequate police case.

Disability pensioner Charlie Foster was sentenced from nine to 12 months in jail in June for consorting with three friends and housemates in the town of Inverell in northern New South Wales.

The consorting offence was revived in the state earlier this year to stop an outbreak of bikie gun violence.

The legislation outlaws repeated communication with convicted criminals, but Foster was an unlikely first target.

Police say neither the 21-year-old, who has an intellectual disability, nor his friends have any bikie links.

Crown prosecutor John Stanhope today advised Armidale District Court that Foster's conviction was based on a police statement of facts that "seems not to disclose all the essential elements".

Mr Stanhope said the statement failed to mention whether Foster received an official warning as required under the law.

Judge Clive Jeffreys has granted Foster leave to withdraw his guilty plea and appeal against his conviction.

Foster's mother, Tricia Harrison, 45, travelled from Inverell to attend today's hearing with her 18-year-old daughter, Macy Foster.

Ms Harrison says police have failed to learn from their experience with the original consorting laws, introduced to tackle Sydney's razor gangs in the 1920s.

"The law was taken away from them, on my understanding, for abusing it and doing exactly what they did to Charlie," she said.

"They gave it back to them and they haven't even used it for the bikies and the drive-by shootings.

"They've targeted a 21-year-old in Inverell who has no affiliation with any bikies or organised crime."

The appeal is being run pro bono by United Motorcycle Council barrister Wayne Baffsky, who successfully challenged previous NSW anti-bikie legislation in the High Court.

Four Sydney bikies are also fighting consorting charges, while more than 100 people have been warned under the law.

Foster's appeal is expected to be heard in Armidale District Court on Tuesday.

If his conviction is quashed, he will remain in Tamworth Jail until next month on lesser convictions.

The judge can also choose to set the consorting conviction aside and send the matter back to a local court.