He stated that since the states make up the Union (country), they (states) had the
right to declare a law null or not valid.
What is this theory referred to as?

john maynard keynes developed new economic theories in response to the stock market crash of 1929. great depression of the 1930s. first and second world wars. economic boom of the 1950s.

b) almost one million irish people died during the potato famine.