Attorney General Merrick Garland will undergo back surgery this weekend, the Justice Department announced Monday. During the procedure, Garland will transfer power to deputy attorney general Lisa Monaco. Garland, 71, will be under general anesthesia during the “minimally invasive” surgery for about 90 minutes on Saturday, said Xochitl Hinojosa, director of public affairs at the Justice Department. He is expected to return home later that day and come back to work Feb. 5. The procedure is to treat spinal stenosis, a narrowing of spaces in the vertebrae. The Justice Department did not reveal whe…