SAN DIEGO -- A lawsuit filed by San Diego and two other counties challenging California's medical marijuana law was rejected Thursday by the state's highest court, but will be appealed to the U.S. Supreme Court, a county counsel said.

San Diego, Merced and San Bernardino counties sued the state in February 2006, claiming federal laws banning marijuana use and possession supercedes Proposition 215, a state measure approved by voters in 1996 that allows pot dispensaries to sell the drug to people who have a doctor's prescription.

The counties' challenge was rejected by the San Diego Superior Court in 2006, and that court's decision was upheld in July by the 4th District Court of Appeal.

The California Supreme Court today declined to review the appellate court's decision.

The lower and appellate courts found that the state's program for issuing ID cards to medical marijuana users is valid and does not violate the state constitution.

San Diego County will appeal the case to the U.S. Supreme Court within 90 days, said Senior Deputy County Counsel Thomas Bunton.