On June 12, 2007, by Decree of President Vladimir Putin he was appointed judge of the Basmanny District Court of Moscow, in 2010 he was reassembled by President Dmitry Medvedev for another six years.
According to The New Times, he came to the judicial system from the military prosecutor’s office.
In August 2011, Arthur Karpov authorized the arrest of the alleged organizer of the murder of the Novaya Gazeta observer Anna Politkovskaya, a retired police lieutenant colonel Dmitry Pavlyuchenkov.
In 2011-2013 he refused to complaints of his mother and colleague Sergei Magnitsky against illegal posthumous persecution and inaction in the investigation of the circumstances of his death. 
In 2012–2016, the judge repeatedly made decisions on the arrest and extending of the deadlines to the defendants of the “Swamp case”.
Since October 2012, he made decisions on placement under arrest and extending his terms to the accused of preparing the riots – Sergey Udaltsov and Leonid Razvoszhaev.
In February 2014, he changed Alexei Navalny preventive measure from a subscription about a non -residence of a house arrest (in the case of Yves Rocher).
In October 2014, he arrested, and later extended the deadlines for preventing the accused in the crash of the Falcon aircraft, the head of Total, Christophe de Margeri in Vnukovo.
In February 2015, Arthur Karpov extended the arrest of the Ukrainian pilot Nadezhda Savchenko.
In June 2016, the arrest of the governor of the Kirov region Nikita Belykh authorized.
In November 2016, he extended the arrest to the Renov to the Renovy manager Evgeny Olkhovik and the T-plus general director Boris Weinziher, accused of giving bribes to the ex-head of the Komi Republic.
In February 2019, he sent under two months the founder of Baring Vostok, US citizen Michael Kalvi, who was suspected of embezzlement of 2.5 billion rubles. From the funds of a credit institution under the guise of a deal with shares.
VChK-OGPU
Judge Arthur Karpov no longer works in the Basmanny court.
“ВЧК ОГПУ”
