The city suffered 127 more homicides in 2015 than in the previous year, Richard Rosenfeld wrote in “Documenting and Explaining the 2015 Homicide Rise: Research Directions,” released this month by the Justice Department.
Rosenfeld identifies three "plausible explanations" behind the increases: a drug market expanding in response to the heroin epidemic, an increase in prisoners being released and a "Ferguson effect," following the deaths of young black men in confrontations with police.
He says any explanation requires additional research. On the Ferguson effect, for example, he calls for more data to answer questions such as: "Does widespread discontent lead offenders to believe they can commit crime with impunity?"
Maryland instituted extremely restrictive gun laws which took effect 1/1/15. They don't mention that and just because it is a only a correlation doesn't mean it isn't a true causation.