Abortion should be banned except to save the life of the mother (everyone has the right to self-defense in libertylover's opinion).
This business of 20 weeks and fetal "viability" is a bad way to measure. Twenty weeks is an arbitrary point based on "viability" in the 1960s. And besides, "viability" is not a fundamental point, it's just a measure of local medical technology since the point of "viability" is vastly different between a neonatal care center in the U.S. as opposed to a hamlet in the middle of Kenya.
The only real solution is to accept the truth: that human life begins at fertilization, (which can be proven with a DNA test). A good ruling would be both timeless and placeless.
Abortion is one of the human miseries inflicted upon mankind by Democrats and other socialist pretending things to be true that aren't true: Slavery was the result of governments pretending that black people aren't people; the holocaust was the result of Germany pretending that Jewish people aren't people; abortion is the result of governments pretending that preborn people aren't people; and the problems are just beginning now that governments are pretending that homosexuality is normal.
Outside the USA both of my kids would have been considered non-viable on the day they were born (both extremely premature), they are both in their mid thirties now and both very successful.