While it is correct to argue that Supreme Court decisions are "case law", the Supreme Court is the final appellate court in the US -- so the only way to change their decision would be through a constitutional amendment.
So, opposing the second amendment is the only way to effectively oppose the rulings related to it (assuming that's what you want to oppose).
[1]: https://en.wikipedia.org/wiki/District_of_Columbia_v._Heller
> While it is correct to argue that Supreme Court decisions are "case law", the Supreme Court is the final appellate court in the US -- so the only way to change their decision would be through a constitutional amendment.
The supreme court does change their mind about things, as the Heller decision demonstrates.
Heller was not a change of mind by the supreme court (it ruled on a different matter to previous rulings -- which had explicitly skirted around the problem of civilian ownership of weapons outside of a military context).
However, even if it were a change of mind -- the supreme court changing its rulings is an incredibly rare event because such events question the finality and authority of their decisions.
Hence why I said "the only way to change their decision would be through a constitutional amendment" -- because waiting for the supreme court to change their mind about it (while technically possible and sometimes the case) is hardly a useful policy position for a political argument.