The notion that it was damaging our democracy to use highly sophisticated computer mapping and micro-targeting of voters to shape congressional districts to one party's advantage wasn't exactly news when Mr. O'Malley got the chance to reshape Maryland's political map after the 2010 census. For years, it had been clear that the two pernicious tactics of the gerrymander — packing huge numbers of voters of the party you want to hurt into a few districts or diluting their power by spreading them out among many districts — was fueling the forces of extremism on both ends of the political spectrum. Members of Congress had little to fear in general elections but lived in terror of primary challenges, leading the House away from compromise and toward sclerotic partisanship.