Lawmakers in Massachusetts, the only state where gay marriage is legal, on Tuesday voted to advance a proposed constitutional amendment to ban gay marriage, a critical step toward putting the measure the 2008 ballot. The proposed amendment, which would define marriage as between one man and one woman but ban future gay marriages, still needs approval of the next legislative session before it can go onto the ballot. The vote Tuesday in the constitutional convention came without debate, immediately after Senate President Robert Travaglini officially opened the joint session. Earlier in the day, Gov-elect Deval Patrick had met with Travaglini...