Rebecca Reider was cleared of all charges at the Nelson District Court relating to the importation of a medicinal marijuana product.

A woman fined $500 for growing cannabis to treat her multiple sclerosis (MS) feels she was dealt "an injustice from the system" after learning another woman charged on the same day received no penalty for her cannabis offences.

Fiona Porter, 45, was "happy" with a Nelson District Court judge's response to her guilty plea on a charge of cultivating nine cannabis plants at the time, but was disgruntled to hear Californian-born Collingwood resident Rebecca Reider, 34, would have no criminal record of six charges related to possessing and importing medicinal cannabis products prescribed in her home country.

"I try to teach my children to be responsible for your own actions. I don't normally break the law, but as an adult I made a conscious decision to do it and I owned up to it," Porter said.

no credit Cannabis law reform advocate Steven Wilkinson says it shouldn't matter whether marijuana used for medical purposes is imported or homegrown.

"[Prescribed medication] doesn't help with the pain at all .... It makes me feel as if my head space isn't there. Sometimes I can't walk, see or talk.

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"Growing dope is not the best idea but it's helped and it's helped lots."

Porter said she knew she was guilty and didn't want to waste "taxpayers' money and effort" by seeking legal representation, but now thinks she would have received a lighter sentence if she had.

She felt it was unfair that Reider, who had several more serious charges than her, could travel to California, where medical marijuana is legal.

"Some people on Facebook say 'why don't you move to California?' Well I can't. I've got a criminal conviction.

"I'm just a bit disappointed. There should be no grey area when it comes to the law."

Although Reider faced a maximum penalty of eight years imprisonment, Judge Peter Hobbs, who also heard Porter's case, determined under the Sentencing Act that the consequences of conviction for Reider were out of proportion with the gravity of the offence.

Reider's lawyer Sue Grey argued that prescribed medication can be bought into New Zealand from overseas and "whether that medication is medical marijuana, or some other drug, was irrelevant under the law," but Porter, who represented herself, said illness was no excuse.

Porter said she blended and drank her cannabis plants to receive their therapeutic benefits without getting high.

She has never applied for permission to use medical marijuana spray Sativex because she thought it unlikely she would be granted funding on top of what she already gets for MS medications.

Those medications took "two years of fighting with Pharmac and then another four months fighting with Nelson hospital to get them to administer it", she said.

Local cannabis law reform activist Steven Wilkinson said the different sentencing for the two women's similar offences was "hypocritical".

"It's still the same product whether it comes from America or here.

"At the end of the day they are both medicating and it shouldn't be a crime to treat any ailment you have for yourself."