Arrests by Philadelphia police dropped by 16 percent during the first half of 2015, the biggest plunge in six years, records show.
And during the same period, all crime - including violent felonies, misdemeanors, and property offenses - increased by 5 percent, according to the latest data posted on the Police Department's website.
Through June, police recorded 5,661 fewer arrests than they did in the first half of last year. Police made 34,786 arrests during the first six months of 2014; this year, 29,125.
The first half of this year marked the first time that arrests have dropped significantly while crime has increased since Commissioner Charles H. Ramsey took over the department in 2008.
Additionally, violent crime, including murder, had fallen steadily in recent years. Last year, for example, violent crime fell 7 percent from the previous year. But during the first half of this year, violent crime stayed the same.
Police spokesman Lt. John Stanford said the drop in arrests in the first half of this year was due in part to the city's new approach to possession of marijuana.
Possession of small amounts is now handled with citations rather than arrests. In the first half of this year, there were 1,216 fewer arrests for marijuana possession. But that accounts for only about a fifth of the overall drop in arrests.
When marijuana possession incidents are removed from the January-to-June figures, the numbers show a 13 percent decline in arrests, with each month lower than last year. Even a 13 percent decline ranks as the biggest drop for a half-year since 2009, a year crime was cut dramatically in Philadelphia.
Stanford said another reason for the drop in arrests was a recent policy change regarding children caught for minor offenses in schools. He said some students who might have been arrested in the past are now put in court programs that do not involve a formal arrest.
That program appeared to have had little impact on the overall decline. Records show there was only a small drop in juvenile cases, a decline of 418 arrests in the first half of the year.
Apart from the reduction in marijuana arrests, some of the biggest drops included 27 percent on weapons offenses and disorderly conduct, and 16 percent on robbery charges.
The drop comes at a time when the nation's attention has been focused on policing, particularly in minority communities.
Philadelphia NAACP president Rodney Muhammad said Thursday that the minority community sees arrests, especially when there are a large number, through two perspectives: The community sees a need for more policing to deal with violent crime, but at the same time sees that petty crimes are over-enforced in minority neighborhoods.
"Stop and frisk, I don't think, has served us well," he said, quickly adding, "There shouldn't be tolerance for violent crime."
That's been part of the national discussion since the riots in Ferguson, Mo., last year.
In July, speaking at the NAACP conference in Philadelphia, President Obama said violent criminals belong in prison, but questioned the arrests of some nonviolent offenders, including juveniles.
"In too many cases," he said, "our criminal justice system ends up being a pipeline from underfunded, inadequate schools to overcrowded jails.
"But here's the thing: Over the last few decades, we've also locked up more and more nonviolent drug offenders than ever before, for longer than ever before," Obama said. "In far too many cases, the punishment simply does not fit the crime."