The Securities and Exchange Commission is considering taking civil action against Standard & Poor’s for its rating of a 2007 mortgage debt offering. Such action could be just the first shot in a legal assault against the major credit rating agencies. The three major agencies — S&P, Moody’s Investors Service and Fitch Ratings — gave high ratings to mortgage investments that turned out to be worthless and contributed to the 2008 financial crisis.

If the SEC charges S&P with violating securities laws, it would mark the first time it’s brought an enforcement action against a top rating agency.