In 1798, faced with the unexpected emergence of a two-party political system during an age of rising authoritarianism, the Federalist Party passed the Sedition Act. The law allowed the Federalists to prosecute their critics among the Democratic-Republicans. The widely unpopular act was allowed to lapse in 1800. In 1859, after John Brown’s private militia attacked Harper’s Ferry, Senator Stephen A. Douglas proposed a new law against seditious conspiracy. In 1861, after Southern states seceded, Congress barred the barn door by passing another Sedition Act, subsequently revised. At its core is a definition of “Seditious conspiracy.”
“If two or more persons in any State or Territory, or in any place subject to the jurisdiction of the United States, conspire to overthrow, put down, or to destroy by force the Government of the United States, or to levy war against them, or to oppose by force the authority thereof, or by force to prevent, hinder, or delay the execution of any law of the United States, or by force to seize, take, or possess any property of the United States contrary to the authority thereof, they shall each be fined or imprisoned not more than 20 years, or both.”
“Conspire,” in turn means “to join in a secret agreement to do an unlawful or wrongful act or an act which becomes unlawful as a result of the secret agreement” or “to act in harmony toward a common end.”
On those rare occasions when the government has prosecuted people for seditious conspiracy, the Justice Department hasn’t often carried away the laurels. In 1920, three Communists were tried, but the judge ruled that the government hadn’t shown any connections between the evidence of sedition and the people charged or that the accused had conspired. In 1936 a bunch of Puerto Rican nationalists were convicted, although it took two trials (along with what supporters of the Nationalists called jury-rigging) to get there. In 1940, members of the anti-Semitic “Christian Front” were prosecuted, but the jury refused to convict. In 1988, a bunch of white supremacists were prosecuted for sedition and other crimes. The case fell apart when the two witnesses—group members “flipped” by the government—turned out to lack credibility. All the men were acquitted. In 1995, the government did manage to convict Sheikh Abdel-Rahman for his role in the 1993 World Trade Center truck-bombing. In 1996, the Justice Department sicced the FBI on Osama bin Laden after his declaration of war on the United States. Apparently, the investigation didn’t get anywhere before 9/11. In 2010, things regressed to the mean when the government prosecuted some “Christian Patriots.” A month into the case, the judge dismissed the most serious charges.
Now a bunch of Oath Keepers and Proud Boys are on trial for seditious conspiracy. The government may have better luck here, what with the whole thing having been on television.
 John C. Miller, Crisis in Freedom: The Alien and Sedition Acts (1951). Probably no coincidence that he wrote at the start of the “Red Scare.”
 Imagine a bunch of U.S. Marshalls showing up at the various legislatures debating Ordinances of Secession and going “You’re all under arrest!”
 The latter isn’t a legal definition. If it was, then the League of Women Voters and wedding planners would be in jeopardy.