"we hold these thruths to be self evident"

https://en.wikipedia.org/wiki/Natural_law

There are. In the constitution, as the court found. There are also reasonable arguments that they are an unavoidable consequence of Human Rights, as described in the declaration of 1789, which is also in the constitution.

The right to privacy is also explicitly in the Code Civil since 1970, in the European Convention on Human Rights and the Charter of Fundamental Rights of the European Union (both are binding to EU member states).

The declaration creates the right. For example, if I believe everyone has a right to use drugs then my interactions with others will respect that (no calling cops on junkies) and I see others who violate that right (police) as immoral. From my point of view the right already exists, most others just don't respect it.

That’s a simplistic view of rights, and ignores other conceptions of rights like natural rights.

Rights are inalienable. You don't grant them by law. You get them when you're born.