"To make all
Laws which shall be necessary and proper for carrying into
Execution the foregoing Powers, and all other Powers vested by this
Constitution in the
Government of the
United States, or in any Department or Officer thereof."
-Article I, Section VIII
This is the "Elastic Clause," also known as the "Necessary and Proper Clause" of the U.S. Constitution. This section of the document allows the government to stay flexible when making certain decisions, thereby giving it the elastic quality. Some people argue that this gives the federal government too much power.
Thomas Jefferson agreed with this when Alexander Hamilton was trying to create the National Bank in the early days of the republic. Jefferson argued that the Constitution didn't create authority for anyone to create a National Bank, but Hamilton used the Elastic Clause to defend his reasoning.
The Elastic Clause created problems with people that had different opinions of what was necessary and proper. This continued until John Marshall dealt with a later National Bank issue. In the case of McCulloch vs. Maryland, Marhshall ruled that the Constitution could be interpreted broadly, and anything that contributed to the feeling of nationalism without harming the United States could be allowed. Therefore, the bank was allowed.