It depends which countries constitution you are referring to.
at least once a year
Congress must meet every 6 months because of the United States Constitution. The Constitution says they must meet at least twice a year.
Every 6 months
At least once each year
Airheads out of control lol they never meet cuss they crazy
At least once every year.
at least once each year
two/thirds of Congress must approve to add an amendment to the Constitution
The Constitution must be fair and passed by congress..........i think
washington dcThey must meet in the same city.