Mr. O’Malley didn’t start off as anything resembling a culture warrior, but he wound up at the forefront of some of the biggest battles on social issues of the day: gay marriage, immigration, the death penalty and gun control. Mr. O’Malley was later than many to throw his support behind marriage equality, but when he did, he lent the full weight of his efforts not only to getting gay marriage legislation through the House of Delegates but also to ensuring that Maryland was among the first states to support it at the ballot box. Mr. O’Malley was a consistent supporter of the state’s “Dream Act,” which granted in-state tuition to some immigrants who lack legal status, and he saw that issue through a popular referendum as well. Moreover, during the crisis of unaccompanied minors crossing the border, Mr. O’Malley both criticized President Barack Obama’s treatment of the children and provided resources to help those who arrived here. Governor O’Malley objected to capital punishment on practical and moral grounds, and he tried repeatedly to repeal it before ultimately succeeding. And Mr. O’Malley enacted some of the most comprehensive new gun control laws in the wake of the Sandy Hook massacre. Despite Maryland’s liberal reputation, none of those was easy or without political cost.