The Second Amendment of the Constitution states,
A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.
As part of the Bill of Rights, the purpose of the Second Amendment is to protect the rights of US citizens—in this case, the right to bear arms—through checks and balances. First of all, the amendment directly limits the legislature from passing laws that prevent citizens from bearing arms. But it also opens the door for the Supreme Court to check the establishment of laws that would infringe on this right.
But throughout the history of the US, various gun laws have been established at both the federal and state levels with the aim of protecting the people. When citizens believe a given gun law is taking away their Constitutional rights, they challenge the law in court. Several cases have gone all the way up to the Supreme Court, which has the authority to strike down a law.
One example is
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