The first ongoing filibuster, a powerful legislative…
March 1841 CE
Senate rules permit a senator or senators to speak for as long as they wish and on any topic they choose, unless "three-fifths of the Senators duly chosen and sworn" bring debate to a close by invoking cloture under Senate Rule XXII
Even if a filibuster attempt is unsuccessful, the process takes floor time.
Defenders will call the filibuster "The Soul of the Senate."
It is not part of the US Constitution, becoming theoretically possible with a change of Senate rules only in 1806, and never being used until 1837.