The Commonwealth’s affordable housing law survived another attack yesterday when Attorney General Coakley refused to certify a petition that would amend the law and dramatically weaken it. The reason for her decision: the petition is “substantially the same” as one that voters in Massachusetts rejected last November. Attorneys from Mintz Levin advocated against the petition on behalf of the Citizens Housing and Planning Association and other nonprofits. Affordable housing advocates should be aware that this doesn’t protect the law from future attack and the petitioners can still appeal the non-certification decision, which would have to be taken up to the Supreme Judicial Court.