Laws that are in place should be obeyed, at least for the time being, because 300M interpretations of the law means chaos. However, that does not mean outdated laws should not be challenged, and changed if deemed necessary. This is really not rocket science. Authorities no longer send debtors to prison, arrest gays, or forbid interracial sex. As our knowledge base and understanding of society and self (hopefully) increases, so too should the law, which should be a servant to society, not some inscribed tablet that must never be touched or changed.
You make reference to rights under the constitution, but many of those rights have changed over the years- they are not fixed. Blacks are now considered people, as are aboriginals, women can vote and do other things in society, couldn't drink (for a while) now we can again. Times change, and the rules of society often to too.
There is nothing sacred about the 2nd amendment, although some lobbyists and extremes will insist there is. It was a no-brainer when first imagined, as most in the country lived a rural or small settlement life, and guns were needed to supplement food supplies, guard against wild animals, and provide safety against the continual friction with aboriginal tribes. Even if the person in question was not needed for a militia, a gun was a logical tool to have. Today the absurdity of having a nation armed to the teeth in a crowded, complex, urban society is made very evident each week, as another mass shooting and tragedy informs Americans of the consequences of slack gun laws.
I have no contempt for freedom of speech, but I do have contempt for gun nuts that cower behind an image of Davy Crockett, or Marshall Dillon, while the kids down the street are getting blown away by an M-16.