That is begging the question. The constitution does not define any of the rights enumerated in the Bill of Rights. The 3rd, 4th, 5th, 9th, 13th and 14th amendments make pretty damn clear that there are limits that the government has in knocking down people’s doors and coming into their private lives. I am unaware that the shorthand of the phrase “right to privacy” was even discussed in that fashion at the time of the framing. But limiting the government’s powers in these areas was.
States police powers were restricted by the 13th and 14th amendments, which by their specific language restricted the power of the state to invade the rights of individuals. A non-lawyer would read these amendments to wholly incorporate in one fell swoop all of the previous rights. However, the USSC has, following the doctrine of deciding only cases before it, only found the 13th and 14th amendments apply as issues were brought up in specific cases through a doctrine called “selective incorporation”. IIRC they have found incorporation for just about everything in the Bill of Rights, with minor exceptions.
In the late 18th century rights did not have to be specifically stated in constitutions or statutes, the “common law” was something that judges announced from the bench for juries to consider when they decided both law and facts. Today juries only decide facts and judges are expected to base their decisions on specific statutes and precedents in their jurisdiction and in the event that they don’t, they are excoriated for being judicial activists, despite the fact that they have the right to decide what the common law is in the absence of statute or binding precedent to the contrary.
The whole school of “original intent” is ahistorical, does not depend on legal or any other scholarship. If it did, the many opinions from the likes of Scalia would cite precedent and scholarly historical papers to show all sides of an issue. The “original intent” school has a right to argue that they are making up their law on the basis of “common law”, but they lack the intellectual honesty to do this, so they invent a whole fake school of “original intent” when in fact the founding fathers rarely agreed on anything but the basics in the Declaration and Constitution. Tellingly they did agree on the 9th amendment which left all undeclared rights to the people. Just as tellingly, once the government was founded and consolidating power, they pretended that the 9th amendment didn’t exist, thereby having the effect of removing many of the sovereign people’s rights. There was substantial debate over whether there should be a Bill of Rights and although the Anti-Federalists lost the debate over whether to ratify the constitution, they overwhelmingly won the debate that there should be a Bill of Rights and in fact won over important Federalists, such as Madison, on that issue. There was substantial debate on what the Bill of Rights amendments would be, and the issue of the people retaining all all rights not limited overwhelming won. (But I go on about my pet issue.)
In our time this is all about the abortion debate. Justice Blackmun wrote a telling history of abortion in the enormously long opinion of Roe v. Wade. Despite the ancients and founding fathers knowing full well what abortion was, they did not mention it at all in the biblical lists of sins, or in the laws of the land. It wasn’t until the late 19th century that US jurisdictions started outlawing it. However, because it was a right as the court declared in Roe v. Wade and reaffirmed many many times, it is a privacy right. It is valid and binding precedent. It would be an abandonment of the principles of stare decisis for the Supreme Court to overturn or eviscerate it on the basis of a change in Court membership as it now has a long history of being upheld. The only constitutional and jurisprudentially sound way to change it would be by constitutional amendment, which has been given very little effort by people who propose abortions be made illegal. Certainly they have legislators who could introduce suitable language, and for all I know they have. But if they have, it has never gotten (sorry) anywhere. I suppose it has never gotten anywhere because they don’t really care whether abortion is illegal, but they love to use it as a political whipping boy to rally the faithful and raise money.
Instead they invent this “original intent” school and form their Federalist Society and their adherents seem hell bent on removing the rights of people to abortion, free speech (locations, times etc.). I don’t want government stronger as against my rights, particularly my first amendment rights which are the ones I use. I want the government weaker in that area. And also weaker in the right to torture people and hold them without review, etc.