Complex sentence: On 15 March 2013 the House approved the legislation by a 82-56 vote and sent the bill to Governor Martin O'Malley, who then signed it into law on 2 May 2013, declaring Maryland the 18th state in the US to ban the death penalty.
Split into simpler sentences: On 15 March 2013 the House approved the legislation by a 82-56 vote and sent the bill to the Governor who will sign it. So with this action, Maryland will become the 18th state in the US to ban the death penalty.