lawyer up

コロラド大学の院生は，映画館無差別殺人の罪で起訴されていますが，事件の動機に関して口をつぐんでいます。
Holmes, 24 was not cooperated with officials as he was held in solitary confinement at a Denver-area county detention facility, Aurora Police Chief Dan Oates said.
“He lawyered up. He’s not talking to us,” the chief said. (JT 2012/07/24)

lawyer upはto stop answering questions during a police interrogation and request a lawyerという意味で，日本語でいうと「口を閉ざす」や「黙秘する」でしょうか（Urban Dictionary）。弁護士などの関係者の困った顔が浮かんできます。（Sugiuchi）