In the constitutions of many other countries, you will find an explicit clause saying (to effect) "rights and freedoms granted by this constitution are not absolute and exceptions can be made to them for sufficiently grave reasons".
Unlike those other countries, the US Constitution never contained such an explicit clause, but the Supreme Court has always read it as if it did. The Supreme Court feels quite justified in doing that, because if you go back and look at the debates in Congress and the state legislatures over the proposal and ratification of the Bill of Rights, it is clear that its proponents always intended it to be interpreted as if such an "exception clause" existed, even though (for whatever reason) they chose to leave it as implicit rather than explicitly putting it in the text.
Unlike those other countries, the US Constitution never contained such an explicit clause, but the Supreme Court has always read it as if it did. The Supreme Court feels quite justified in doing that, because if you go back and look at the debates in Congress and the state legislatures over the proposal and ratification of the Bill of Rights, it is clear that its proponents always intended it to be interpreted as if such an "exception clause" existed, even though (for whatever reason) they chose to leave it as implicit rather than explicitly putting it in the text.