Sedition is defined as actions or words intended to lead to or encourage the overthrow of a state. Most nations have laws against sedition, although nations which value free speech have tried to protect their citizens' right to criticize their governments, differentiating it from, for example, anti-war protests. This has not always been the case, however, and numerous nations have a history of oppressive anti-sedition laws which have been used to prosecute social minorities. Some countries also have very oppressive laws that are designed to suppress opposition parties or candidates, sometimes with very serious penalties.
Treason is sometimes confused with sedition, but the two crimes are actually different. Sedition encourages overthrow, but the person who commits it does not actively participate in situations designed to lead to overthrow of the government. Holding a revolutionary meeting in your home is sedition; sheltering soldiers of an enemy is treason. A treason conviction requires clear evidence that the criminal actively engaged in a scheme to destabilize the current government, and that he or she is a citizen of the nation being threatened. The two crimes are punished differently, and treason is generally regarded to be more serious.
In the United States, several sedition laws have been enacted and later struck down, including the Sedition Act of 1798 and the Espionage Act of 1917, which was designed to put a stop to anti-war speeches and protests. In the American South, the Confederacy used such laws to prosecute abolitionists before and during the Civil War. In other nations, laws vary, depending on who is in power, and the type of government in place. In modern times, several nations, including Australia and the United States, have included language about sedition in laws designed to combat terrorism.
Prosecution for an act of sedition is relatively rare, but does happen. Sometimes individual terrorists are charged with it because, technically, they are not committing treason, since the act of violence is not being committed against their own nation. In nations that protect speech, making an anti-government speech or writing about the government is not considered sedition, unless the author takes the additional step of encouraging the audience to rebel. Lobbying for a legal change of government through election or petition is also protected, and citizens are also usually free to protest or speak out about flaws within their governments.