hit a new low

すでに取り上げられているようにJustin Bieberの問題行動が止まりません。今度はスピード違反と飲酒運転で逮捕されました。http://d.hatena.ne.jp/A30/20140124/1390550410
lowは「安値, 最低価格；（温度数字などの）最低値；低水準」を意味し，hit a new lowで「新底値をつける」という意味があります（『プログレッシブ英和中辞典』小学館）。ここでは「またも（不祥事で）評判を下げる」という意味でしょう。ちなみに Daniel Powterの"Bad Day"というよく知られた歌の中にもこの表現が出てきます。（Koyamamoto）

Singing or sinking? Justin Bieber hits new low
LOS ANGELES — For more than a year, Justin Bieber has had more tabloid hits than Billboard hits: The singer’s music career has taken a backseat to his wild boy antics, and a new arrest for a DUI charge marks a new low for the Grammy-nominated pop star.
Bieber’s arrest Thursday is another sign of the crazy lifestyle that has taken over the 19-year-old’s image — but a more serious one given the gravity of his alleged offenses. Authorities say Bieber failed a field sobriety test early Thursday and he is facing driving under the influence charges after driving nearly twice the speed limit on a Miami Beach street. Police said he also resisted the arrest and smelled of alcohol.
http://www.japantoday.com/category/entertainment/view/singing-or-sinking-justin-bieber-hits-new-low