The Ministry retained a high level of autonomy and a remarkable amount of freedom of operation within the Soviet system, as the agency was only responsible to the Central Committee. MGB agents had the power to arrest and sentence opponents upon receiving approval from a higher authority, a clause oft ignored. The OSO (the Special Council of the State Security Ministry) convicted arrestees charged with committing political crimes, including espionage, and could banish them from certain areas, or from the USSR entirely. In Stalin’s last years, between 1945 and 1953, more than 750,000 Soviet citizens were arrested and punished. Many of the arrests made by the MGB were founded on flimsy or fabricated evidence, most notably on the "suspicion of espionage" (podozreniye shpionazha, or PSh). Since in many cases it is impossible to prove any espionage activities or even an intention to spy, the case is built on the "suspicion of espionage", making acquittal impossible.