The Congress of the United States is a good example of a sui juris institution. The two chambers of the Congress convene by their own right as defined in the US Constitution (Twentieth Amendment) on January 3 every year. The US President does not have to invite or call the Congress to assemble for regular sessions, but he has the option to call special sessions. Thus, in the United States, the legislature functions independently of the executive, but there are some checks and balances.