Letitia Pepper, attorney and director of Crusaders for Patients' Rights, will argue the ban violates the California Environmental Quality Act, which more often is used to determine the environmental impact of a development.
The Board of Supervisors approved an ordinance in March 2011 to ban medical-marijuana dispensaries in unincorporated areas and to limit cultivation of marijuana by valid patients to indoors only.
A lawsuit filed by Pepper challenging the county's ban is scheduled for an 11 a.m. hearing Friday at San Bernardino Superior Court, 303 W. Third St., San Bernardino.
"This is the first lawsuit under CEQA I'm aware of that's been filed," Pepper said.
The lawsuit was filed shortly after the county adopted its ordinance.
"There's no possible way anyone could see it not having an impact on the environment," Pepper said of her lawsuit, which will show the county's ordinance has had an impact on the physical environment.
"People think about it in terms of cutting a forest down but the environment includes man-made environment," Pepper said.
"If you can imagine the county adopting an ordinance where they banned all pharmacies ... where people would look for a Rite Aid or Walgreens and they're banned. That's an impact on the physical environment.
California voters in 1996 approved Proposition 215, which allows people with a medical need for marijuana to use it. Federal law bans the usage.
Pepper said she has asked for medical-marijuana patients to attend the hearing so the judge can see the support out there for the issue.
Lanny Swerdlow, Marijuana Anti-Prohibition Project member, said he expects at least 20 medical-marijuana patients to attend.
David Wert, spokesman for San Bernardino County, said he was unaware of the lawsuit, but the board's rationale in deciding the ban was marijuana "is something that is sought after by potentially dangerous people and growing it outside invites the criminal element to raid backyards or other outdoor places to get their hands on their valuable crops.
"What the county had in mind was what we often see in remote areas of the state ... Marijuana farms become armed camps, and armed people try to steal the crops, and the county believes that's not something the neighbors of marijuana nurseries should have to endure."
California Environmental Quality Act, which was passed in 1970, requires an analysis on potential environmental impacts from a proposed development in a city, county or the state. The act determines the environmental impact but also provides alternatives to mitigate the issues.