The south-western 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 and Aids, cancer, glaucoma, and multiple sclerosis and epilepsy, according to a news release from Richardson's office.
California began allowing similar use of marijuana 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 and Aids.