New Mexico doctors are allowed to prescribe marijuana to help some seriously ill patients manage symptoms, including pain and nausea, under a bill signed into law by Gov. Bill Richardson on Monday.

“This law will provide much-needed relief for New Mexicans suffering from debilitating diseases,” Richardson, a Democratic candidate for U.S. president in 2008, said at the signing ceremony. “It is the right thing to do.”

The southwestern state is the 12th in the United States to endorse the use of marijuana for medical uses. New Mexico’s state legislature is the fourth in the country to enact such a measure.

The law allows marijuana use by patients suffering from several conditions, such as HIV/AIDS, cancer, glaucoma, and multiple sclerosis and epilepsy, according to Richardson’s office.

U.S. states that have backed medical marijuana have, however, come into legal conflict with the 1970 federal Controlled Substances Act barring marijuana. Courts have said federal law trumps state law.

Just last month, the 9th U.S. Circuit Court of Appeals ruled a California woman with an inoperable brain tumor may not smoke marijuana to ease her pain even though California voters approved its medicinal use in 1996.

In 1978, New Mexico began allowing very limited use of marijuana, or its active ingredient, THC, to help control cancer patients’ nausea and vomiting caused by chemotherapy, but only when other nausea-control drugs failed.

The law creates a panel of eight expert physicians and other health care workers to supervise the program. Qualified patients must be under a doctor’s care and supervision, the news release said.

“I would like to thank the governor for…giving me another shot at life,” said Essie DeBone, who suffers from advanced complications from HIV/AIDS.