Roe, Dobbs, and the Penumbra Theory of Constitutional Rights (a quick tutorial)
Roe (1973) relied on a theory of constitutional law called the Penumbra Theory.
In Roe, the US Supreme Court decided that certain abortions are guaranteed by the "right to privacy."
But "privacy" is not mentioned in the Constitution.
What happened was that in a series of cases leading up to and including Roe, the Court slowly built up the case that certain rights that are not explicitly mentioned in the Constitution are NECESSARILY IMPLIED by the existence of other rights that ARE explicitly mentioned.
For example: If I told you that you can sleep in my house, it's necessarily implied that I have a house. If I didn't, my offer to you would be meaningless.
Similarly, the Court argued in Roe, we must assume there is a right to privacy if we want to make sense of some of the other rights that are mentioned in the Constitution (for example, the Fourth Amendment right against unreasonable searches and seizures).
Hence, the Penumbra Theory -- Penumbra means a space of partial illumination (as in an eclipse) between shadow and light.
Conservative judges have hated the Penumbra Theory because they tend to strictly adhere to what is written in the text of the Constitution (or so they claim).
Even some liberal Constitutional scholars believed that there were better arguments to underpin Roe -- for example, the Equal Rights Clause of the 14th Amendment. (Women are not treated equally to men if they're forced by the State to bring pregnancies to term, and everything that goes with that.)
Would it have made a difference? Perhaps not.
Amy Coney Barrett, for example, said during oral arguments in Dobbs that personal and practical impediments to women’s equality are now gone -- we have achieved equality 🤷🏽♂️