Countries that have a one-party system include the three communist states of North Korea, China, and Korea, as well as Iraq. In the 20th century, one of the most prominent examples of a state with a one-party system was the Soviet Union. A common feature that is shared in countries with one-party systems is the banning of political opposition by law.
In a single-party state, the local constitution is commonly worded to ban the transfer of a power from the ruling party to another party by limiting either legal existence or participatory ability in elections and decision-making. The justification of the existence of single-party states most typically relates to national unity and a legitimization of the party's continued dominance of power by connecting their presence as part of the will of the people.
In the 20th and 21st centuries, a large portion of single-party states were established following the Marxism-Leninism ideology. Exceptions include Nazi Germany and Italy under Mussolini, which followed a fascist dogma. Some other single-party states that emerged after World War II originated from former colonies in which the ruling party played a major or complete role in achieving independence, such as Cameroon and Indonesia, though the period of single-party rule in these countries were generally brief.