The House of Delegates passed limitations that give Maryland the most stringent evidence requirements of any of the 35 states that permit capital punishment, The Sun newspaper in Baltimore reported Friday.
"While it is not the full repeal that we had hoped for, I want to thank the Maryland House of Delegates for voting to strengthen Maryland's death penalty law," O'Malley said in a statement following the Thursday vote.
Death penalty advocates told The Sun the new law is so restrictive it will, in effect, "nullify" capital punishment.
The measure limits capital cases to those with biological or DNA evidence, a videotaped confession or a videotape linking the defendant to a homicide, The Washington Post reported.
"You have cleverly and successfully killed the death penalty in Maryland," Del. Patrick L. McDonough, R-Baltimore County, said.