But the experience of Maryland and the eight other RGGI states suggests they would be foolish to do so. Republican former Gov. Robert L. Ehrlich Jr. initially kept Maryland out of RGGI for fear that it would drive up electric rates and cause rolling brownouts or blackouts, but by the end of his term, he signed a law that required Maryland's participation. Nearly a decade later, Maryland has a new Republican governor, Larry Hogan, and he's making no move to pull the state out of RGGI. Being part of RGGI "has been useful," Ben Grumbles, Mr. Hogan's secretary of the environment, said in a recent interview with The Sun's editorial board. "It was smart for the state to have been involved."