Public outrage over several recent murders has prompted politicians and crime-weary citizens to demand that dangerous criminals be locked away for life. But the get-tough campaign is colliding with the reality of a prison system bursting at the seams. The federal prison system is 37 percent over-capacity, while budget-strapped states are housing prisoners in tents, hallways and gymnasiums -- or releasing them early. Conservatives cite government's duty to protect the public and argue that investing in new prison construction will pay off in long-range crime reduction. Liberals criticize the national trend toward mandatory sentences -- enacted largely as part of the “war on drugs” -- as a wasteful approach that is unaffordable and unlikely to cut crime.