It really depends on which state you live in. Some state it is easy to amend their constitutions while with others the process is difficult.
To change the US Constitution you need a 2/3rds majority from Congress. I believe with state constitutions you have to have a petition with a certain number of signatures, which is hard to do, then the signatures must be checked to make sure they are authentic meaning the people who have signed the petition are from the state and they actually exist. Then it goes to the State, which they will look at the petition and I believe the State gives it to lawyers too look at and then a Judge must also look at it. If the judge disagrees, the process must start all over again.
The Antiballistic Missile Treaty was created because the countries involved needed limitations on the ways that the they could use anti-ballistic missile systems. The treaty was signed by two countries: the United States and the Soviet Union. In 2002, the United States withdrew from the treaty since it was the only remaining party that followed the treaty. After the United States withdrew from the treaty, it was terminated.
Taxation on sugary drinks is an effective intervention to reduce sugar consumption (8). Evidence shows that a tax on sugary drinks that rises prices by 20% can lead to a reduction in consumption of around 20%, thus preventing obesity and diabetes.