The Justice Department is filing civil charges against the credit rating agency Standard & Poor’s for improperly rating mortgage securities leading up to the nation’s financial crisis. The charges would mark the government’s first enforcement action against a major credit ratings agency to come out of the nation’s near-economic collapse. But they would only carry civil penalties of fines and new restrictions — not jail time for top executives. Prosecutors reportedly decided to file the civil case after S&P balked at paying fines of at least $1 billion.