Political freedom is relative to what state systems will tolerate. There are therefore degrees of repression at all times everywhere, which may range from deterrent persuasion to sanctions, to incarceration, to the murder of dissidents in society by the state. Repression of political views, organizations and actions felt to be detrimental or subversive to a nationally accepted or imposed norm includes: the banning of political parties, literature and activities; internment; torture; disenfranchisement; confiscation of property; and maltreatment of families of offenders. The results may be political apathy, ignorance, alienation and instability or foreign intervention, international conflict, and war. Political repression may take the form of foreign intervention and may be particularly intense during war.
Police states, and governments active in political repression, are aided by technology. Some of the equipment and techniques used in controlling and penalizing victims of the state include sensory deprivation, electronic surveillance, and a range of computer software for citizen-victim 'files', data bases and non-conformist behaviour detection. The supplying of such instruments of government repression is an industry having its own suppliers, much like the defence industry, and some manufacturers supply arms, ammunition and various devices both to state police apparatus and to the military. Countries which pride themselves on their political freedom may in fact have lucrative industries which supply such instruments of repression to the governments of other, less politically free, nations.
Notable instances of political repression are reported to occur in Iran, USSR, South Africa and Brazil, among others. Repression of student activists is a frequently witnessed phenomenon. In the past decades it has been associated with Berkeley, Columbia, and Kent State in the USA, and with universities in Paris, Louvain, Caracas and Valencia (Venezuela). Other notable acts of repression are the now famous cases of dissident Soviet writers, and the foreign intervention in Hungary, Czechoslovakia and Afghanistan by the USSR. That political repression can result in murder or long-distance assassination was seen in the case of Leon Trotsky. However, political repression of intellectuals may often be due to the fact that they may be acting as spokesmen (whether students, artists, or theorists) for the masses.