On January 6th, 2021 following a ‘Save America’ rally held by President Donald Trump, supporters violently attacked the U.S. Capitol with the aim to stop Congress’ verification of election results certifying President elect Joe Biden. The subsequent press coverage on this tragedy provided a variety of labels for the violence: insurrection, rebellion, riot, protest, etc. To understand what type of act this was, I utilize Thomas Aquinas distinction of ‘sedition’ and ‘rebellion’ as a conceptual model. I argue that the attack on the Capitol was a form of political sedition, which Aquinas held to be an immoral and unjustified attack on proper political authority. In connection with this claim, I discuss Aquinas’ political theory and his criteria of a justified armed rebellion against political tyranny as a way to understand the events at the U.S. Capitol and to help us think clearer about legitimate and illegitimate civilian political violence in the future.