Facing the Ballarat Magistrates' Court, Jason Foster said he worked with organisations and governments "here and abroad" to reform laws around cannabis.

Representing himself, he said this was his first time in court, with no prior convictions, and he only intended to use the plants himself.

According to the police summary, the Ballarat divisional response unit found nine plants, four seedlings, a container of seeds, and three bags of cannabis after raiding his address in March.

He made partial admissions in a police interview at the time, but made further admissions in court.

Foster said he has used cannabis for medicinal purposes for more than 30 years, and now consults for companies and works for cannabis advocate groups.

"I know it was against the law, I use it for pain relief, and grow it for my own use to avoid the illicit black market," he said, noting a conviction would make travel and political work difficult.

He also submitted a reference from "the head" of Drug Policy Australia, which describes itself as a public health NGO on its website, and asked the court to consider an adjourned undertaking.

Magistrate Ron Saines said that was not on the table, as Foster has "an ambition to change the law, you have an intention to continue using".

"I don't treat it as an act of disrespect, but it would be a falsehood," he said.

"You, and this court, are at the intersection of law and public debate.

"I'm fully aware of the views that are expressed in some sections of the country, with the therapeutic benefits, as well as the detrimental aspects, which could cause deterioration in mental health - whether there's truth in that is debatable, but it's incomplete and not a debate that goes on in courts."

Instead, he fined Foster $800, plus costs, but withheld a conviction.

He warned Foster he could face further penalties if he continued.

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