Maryland has become the first Southern state to abolish the death penalty and the 18th such state in the nation.
"We have a responsibility to stop doing those things that are wasteful and ineffective.” Governor Martin O’Malley said.
O’Malley signed the measure at a ceremony on Thursday, attended by Kirk Bloodsworth, the first person in the US on death row to be found innocent with the help of DNA evidence.
The bill will not apply to five men currently on death row, though their cases may be individually evaluated with the potential for life in prison without parole.
State Senator Jamie Ruskin said he believes the pressure is building around the nation to use law enforcement resources to lower the homicide rate.
"The trend lines are clear," Raskin said. "There's nobody who's adding the death penalty to their state laws. Everybody is taking it away."
Supporters of capital punishment said O’Malley was stripping the state of an important tool to protect the public. Del. Neil Parrott, a Washington County Republican, also criticized the governor for moving ahead with banning the death penalty while pushing a gun-control bill to restrict firearm access to citizens.
The bill could still be petitioned to the 2014 ballot, if Parrott receives 18,000 signatures by May 31.
Ben Jealous, president and CEO of the NAACP, said O’Malley’s move was political. The governor aspires to run for president, and abolishing the death penalty could aid him in achieving a victory.