VANCOUVER – The Conservative government has lost its latest attempt to prevent medical marijuana users from growing pot at home, with the Federal Court of Appeal upholding an injunction that exempted patients from a massive overhaul of the system.

New rules were introduced earlier this year that prohibited home growing and instead shifted production to commercial operations, but a group of patients is challenging that regime in a case expected to be heard in the new year.

A Federal Court judge issued an injunction in the spring that allowed patients who were authorized to grow and possess marijuana under the old system to continue to do so until their case is resolved.

The government appealed, but the Appeal Court released a unanimous decision Monday upholding the injunction.

“It’s very significant,” Kirk Tousaw, a lawyer for the four plaintiffs in the case, said in an interview.

“The big fear was that if the government’s appeal was successful, then all of these people who have been protected by the injunction could very well turn into criminals overnight.”

The previous medical marijuana regime, which was introduced in 2001, allowed patients to either grow their own pot, designate someone to grow it for them, or purchase it directly from Health Canada.

New regulations took effect this last spring that no longer allowed personal production and instead established a system of federally licensed commercial producers. There are now 15 such operations selling medical cannabis.

The plaintiffs filed a constitutional challenge arguing the updated regulations violate their right to access important medicine, because commercial prices are considerably more expensive under the new system. They also complained the commercial market wouldn’t give them as much control over which strains of the drug they use.

The Federal Court trial is set to begin in February. The injunction preserves patients’ right to grow their own marijuana at least until a decision is issued.

Two of the plaintiffs also filed a cross appeal, arguing the Federal Court injunction was too narrow and left out some patients because of the dates outlined in the injunction.

The Appeal Court ordered the lower court to reconsider the terms of the injunction to clear things up.

As of last year, nearly 38,000 Canadians had received authorizations under the old system, the vast majority of whom chose to grow their own marijuana rather than buy it from the federal government.

Health Canada says it does not know how many patients continue to grow their own marijuana because of the injunction.

More than 13,000 patients have registered with the new licensed producers, which together sold 1,400 kilograms of dried marijuana between Jan. 1 and Oct. 31. Prices range from as low as $2.50 a gram to as high as $15, though most are between $8 and $10.

Follow @ByJamesKeller on Twitter