FILE - In this March 1, 2012 file photo, Maryland Gov. Martin O'Malley signs the Civil Marriage Protection Act in Annapolis, Md., becomingthe eighth state to legalize same-sex unions. O

 

              FILE - In this March 1, 2012 file photo, Maryland Gov. Martin O
FILE - In this March 1, 2012 file photo, Maryland Gov. Martin O'Malley signs the Civil Marriage Protection Act in Annapolis, Md., becomingthe eighth state to legalize same-sex unions. On Tuesday, the US Supreme Court will begin hearing two days of cases involving gay marriage. (AP Photo/Patrick Semansky, File)