Insurrection

A violent uprising or rebellion against an established government or authority, falling short of a full-scale revolution. The U.S. Constitution provides specific mechanisms for dealing with insurrections, including the suspension of habeas corpus and the deployment of the militia.

Example: The Enforcement Act of 1871 (also known as the Ku Klux Klan Act) was passed by Congress to combat insurrection and domestic violence in the South that was depriving citizens of their constitutional rights during Reconstruction.

Common misconception: Insurrection and treason are the exact same legal concept. Treason is specifically defined in the Constitution (Article III, Section 3) as levying war against the U.S. or adhering to its enemies, requiring a high burden of proof. Insurrection is a broader statutory crime involving organized rebellion against governmental authority.

Sources: https://constitution.congress.gov/browse/article-1/section-8/ — Constitution Annotated, Art. I, §8 (calling forth the militia "to execute the Laws of the Union, suppress Insurrections"); https://uscode.house.gov/view.xhtml?req=(title:18 section:2383 edition:prelim) — 18 U.S.C. 2383, the federal insurrection statute; https://www.govinfo.gov/ — Enforcement Act of 1871 (Ku Klux Klan Act), 17 Stat. 13 (42nd Congress)