In order to reduce uncertainty and avoid unnecessary arrests, SB 420 established "limits" or guidelines as to how much marijuana patients and their caregivers could grow and possess. The state default SB 420 guidelines are 6 mature plants or 12 immature plants per patient, and 8 ounces of dried marijuana bud or equivalent. By state law, individual counties and cities are allowed to set higher but not lower limits; however the courts have now ruled that cities and counties may outlaw cultivation altogether. (Read more and see list of local SB 420 guidelines ). Individual patients may exceed the guidelines if they have a doctor's note saying they need more; in practice, however, police routinely ignore this exception and there has been much backlash over doctors issuing so-called "cultivation certificates" for up to 99 plants.