Poverty cannot be the primary reason, says Jack Levin, a criminologist at Northeastern University in Boston.

ECONOMIST: Oakland

Jack Levin, a criminology professor at Northeastern University in Boston, acknowledges the success of policing strategies, but notes that an ageing society like the United States should expect to experience less violent crime.

ECONOMIST: The great crime decline continues. No one is sure why

But background checks would not have stopped most school shootings, in which the gunmen took legally obtained weapons from parents with spotless backgrounds, says Jack Levin, a professor of sociology and criminology at Northeastern University in Boston.

BBC: US gun debate: Could Obama's guns plan work?

Jack Levin, a professor of sociology and criminology at Northeastern University in Boston, pointed to several factors behind the strength of white supremacist groups, including a flagging economy and the election of the country's first black president.

CNN: STORY HIGHLIGHTS

Democratic Senators Jack Reed and Carl Levin are sponsoring an Amendment to start U.S. troop withdrawal this year.

NPR: Debate on Iraq Timetable Moves to Senate

This is most obviously the case with respect to a proposal to begin removing U.S. forces from Iraq advanced by Democratic Senators Carl Levin of Michigan and Jack Reed of Rhode Island.

CENTERFORSECURITYPOLICY: Call it surrender