New York Police Department Commissioner William Bratton attends a press conference after witnessing police being retrained under new guidelines at the Police Academy on Dec. 4. Andrew Burton/Getty Images hide caption

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New York City Police Commissioner Bill Bratton speaks during an NYPD swearing-in ceremony in New York on Jan. 7. He confirmed to NPR today that there had been a work slowdown by officers in the weeks since two police officers were shot dead. He said the matter was being corrected. Seth Wenig/AP hide caption

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New York Police Department Chief of Detectives Robert Boyce said Sunday that a gunman told bystanders to follow him on Instagram, then shot and killed two police officers in Brooklyn on Saturday. Stephanie Keith/Reuters/Landov hide caption

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Thousands gathered on the National Mall last week to protest the deaths of Eric Garner and Michael Brown. Some law students say their involvement in the protests means their exams should be postponed. Saul Loeb/AFP/Getty Images hide caption

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Congressional staff members gather at the Capitol to raise awareness of the recent killings of black men by police officers, both of which did not result in grand jury indictments, on Dec. 11. They are joined by Rep. Elijah Cummings, D-Md. (second from left), and Senate Chaplain Barry Black (far right). J. Scott Applewhite/AP hide caption

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Melissa W. Green, right, and her daughter Reshae Green holds up their signs at Freedom Plaza during the "Justice for All" march and rally on Pennsylvania Avenue in Washington on Saturday. Jose Luis Magana/AP hide caption

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