The U.S. Supreme Court has declined to hear case #08-887 San Diego County v. San Diego NORML et al., leaving in place a state appeals court ruling holding that California's medical marijuana laws "do not pose a significant impediment" to the federal Controlled Substances Act because that law is designed to "combat recreational drug use, not to regulate a state's medical practices."

San Diego filed suit after San Diego NORML threatened to sue the county for failing to implement the state ID card program mandated under SB 420, a law the state legislature passed to implement the voter-approved Prop. 215. In return, the county sued the state and San Diego NORML. The ACLU, Americans for Safe Access and the Drug Policy Alliance joined as patient intervenors against the county in 2006.

The San Diego lawsuit, which was joined by San Bernardino and, for a time, Merced counties, argued that counties could not be required to establish the ID card system because to do so would violate federal law.