Warning: The following contains SPOILERS for the Republic of Sarah pilot.
The pilot episode of The Republic of Sarah closes with its heroine Sarah Cooper (Stella Baker) being arrested by the FBI for conspiracy against the authority of the American government. The legalities of this situation raise several questions regarding the premise of the series and the real-world laws it references. Chief among these questions is whether or not someone can be charged with sedition against the American government if they are not an American citizen or if an American city or state could legally withdraw from the United States.
One of several original series introduced to The CW in 2021, The Republic of Sarah is set in the fictional town of Greylock, New Hampshire. When the town is threatened by a corrupt mining company that uses the backing of the state's governor to seize control of the town, school teacher Sarah Cooper starts looking for a way to save her city. This leads to the discovery that Greylock was never officially incorporated into either the United States or Canada, due an unresolved conflict regarding where the border was set on the official surveyor maps. While Sarah brought this point up only intending to slow down the mining company, she suddenly found herself placed in charge of the city government after the people voted to assert their independence and the mayor resigned. The pilot ended with Sarah holding a press conference to announce Greylock's independence to the world and being arrested by the FBI for violating U.S. Code Title 18, Section 2384, which covers Seditious Conspiracy at the federal level.
The legalities of secession have been a frequent topic of conversation in the United States in recent months, which many suggesting it would be better if various states formed their own countries. The United States Constitution outlines a process for inducting new states into the nation but has no rules regarding them leaving the United States. Secession itself is not explicitly illegal, but associated actions like treason, sedition, rebellion, and insurrection are federal crimes, as defined under U.S. Code Title 18, Chapter 115. Additionally, while secession might not be illegal, most legal scholars believe the American Civil War established that there is no legal right for secession either. This was codified in the 1869 case Texas v. White, where the United States Supreme Court held that individual states could not unilaterally secede, even with a full vote by their legislative bodies.
Despite this, some have argued that American states do have a right to leave the United States. Most of these arguments are based around the state of Texas, which did operate as an independent nation for nine years after winning its independence from Mexico in 1836. When Texas was brought into the United States by the 1845 Joint Resolution for Annexing Texas to the United States, it was stipulated that the state government could vote to break itself up into no more than five smaller states. Ignoring the question of whether or not that agreement would still stand today after Texas joined the American Confederacy in 1860, the Joint Resolution speaks only of making new states out of Texas; not allowing these new states to become their own countries.
However, this is technically different from the situation set up in The Republic of Sarah. Secession can only occur when a body decides to leave a larger legal body that it was already connected to in some form or fashion. Greylock's contention that it was never part of the United States is an entirely different issue, though the federal government might dispute their claim and treat it like secession, which is what seemed to happen when the FBI arrested Sarah Cooper after she publicly declared the town's intention to become its own nation. As for the legality of Sarah's arrest, there is nothing in U.S. Code Title 18, Section 2384 which says one must be an American citizen to be arrested for Seditious Conspiracy, only that you have to "prevent, hinder, or delay the execution of any law of the United States," which is an entirely different crime than committing treason.