Fleshing Out The Rationale For Privacy Rights

One concern for me over the years is that we have a "right to privacy," but there aren't too many cases where it is discussed in depth. The matter is basically taken as a matter of course, precedent cited, maybe a quote from Brandeis' dissent in Olmstead.  I don't think the substance of the matter is even talked about that much in Fourth Amendment cases, which tend to be a matter of applying some rule or dealing with some fact situation.

The 1920s cases of Meyer and Pierce are early privacy cases, part of various cases with related concerns involving educational regulations that were motivated by WWI and other topical concerns. This includes preventing certain schools from teaching in a non-English language or requiring parents to send their children to public school.  These might now be understood as freedom of speech or religion cases, but  they were expressed as general liberty cases:

Without doubt, ["liberty" in the Due Process Clause] denotes not merely freedom from bodily restraint, but also the right of the individual to contract, to engage in any of the common occupations of life, to acquire useful knowledge, to marry, establish a home and bring up children, to worship God according to the dictates of his own conscience, and generally to enjoy those privileges long recognized at common law as essential to the orderly pursuit of happiness by free men.

Various cases were cited though other than economic liberty cases am not aware of  cases where state laws were struck down by the Supreme Court as a violation of such liberties before that time.  Nonetheless, it was not novel to deem marriage and raising children as "liberties" protected from state violation by court review if the regulations were too unreasonable.  The two cases, as usual for Justice Reynolds opinions, are not overly expansive.  But, Pierce does summarize:

The fundamental theory of liberty upon which all governments in this Union repose excludes any general power of the State to standardize its children by forcing them to accept instruction from public teachers only. The child is not the mere creature of the State; those who nurture him and direct his destiny have the right, coupled with the high duty, to recognize and prepare him for additional obligations.

Meyer contrasts what another regime set forth:

In order to submerge the individual. and develop ideal citizens, Sparta assembled the males at seven into barracks and intrusted their subsequent education and training to official guardians. Although such measures have been deliberately approved by men of great genius, their ideas touching the relation between individual and State were wholly different from those upon which our institutions rest, and it hardly will be affirmed that any legislature could impose such restrictions upon the people of a State without doing violence to both letter and spirit of the Constitution.

This has shades of Justice Douglas' dissent in Poe v. Ullman.  It suggests a type of structural concern, here not separation of powers, but of liberty itself.  "Liberty"  in this country provides for a certain zone of freedom, including for parents in the raising of future voters.  This is not just a matter of freedom of speech or religion, but a matter of parental rights that also reach to individual liberty generally.  They are not mere "creatures of the state," but have a zone of privacy and autonomy that the government must not violate without good cause.  As noted:

It is well known that proficiency in a foreign language seldom comes to one not instructed at an early age, and experience shows that this is not injurious to the health, morals or understanding of the ordinary child.

This is somewhat conclusionary at best and two justices dissented.  But, the value of showing your work here does not negate the wider point.  As Justice Douglas wrote more than a decade before Griswold regarding the "liberty" of a right to privacy:

The right of privacy should include the right to pick and choose from competing entertainments, competing propaganda, competing political philosophies. If people are let alone in those choices, the right of privacy will pay dividends in character and integrity. The strength of our system is in the dignity, the resourcefulness, and the independence of our people. Our confidence is in their ability as individuals to make the wisest choice. That system cannot flourish if regimentation takes hold. The right of privacy, today violated, is a powerful deterrent to any one who would control men's minds.

And, just like Congress has a "necessary and proper" clause to help them out to further enumerated powers by doing things not expressly allowed, the Ninth Amendment reminds that rights are present that go beyond those enumerated.  When determining what these are, you can use various techniques such as  "those privileges long recognized at common law as essential to the orderly pursuit of happiness by free men" (pursuant to changing developments), those necessary to further enumerated rights and general rights that are fundamental to liberty.

Privacy overlaps here.