Abortion will not immediately become illegal nationwide. Instead it would be up to each state to decide how much access women living there would have to abortion.
About half of the 50 US states will move to ban abortions within weeks, many immediately. But other states will continue to provide access, not just for women in their state but for those living in states where it will be banned.
There are 13 states that have so-called trigger laws in place, which would lead to an immediate ban if the Supreme Court rules to overturn Roe v Wade. They are Arkansas, Idaho, Kentucky, Louisiana, Mississippi, Missouri, North Dakota, South Dakota, Tennessee, Utah, Texas, Oklahoma, and Wyoming.
Another dozen or so may move quickly to ban or severely limit access, says the Guttmacher Institute, a pro-choice group. It estimates 36 million women of reproductive age would live in states without abortion access. It would most affect poor women and those from ethnic minorities, says the institute.
A majority of Americans (62%) told Pew Research in 2019 that abortion should be legal in all or most cases. Only 38% said it should be illegal in all or most cases.
The Supreme Court has been asked to rule on a Mississippi law that challenges Roe v Wade. The court is made up of nine justices who serve on the bench for life.
President Donald Trump appointed three during his presidency, when vacancies on the court came up. That changed the political leaning of the court to one that was more sceptical about Roe v Wade and more supportive of restricting access to abortions.
All three of Trump's appointees reportedly voted to overturn. At the same time, many Republican states around the country have been focusing their attention in recent years on bringing in more restrictive laws.
It is very rare that rulings made by the Supreme Court are made public ahead of time, although it did happen with the historic 1973 ruling at the centre of this case. The document, published by the Politico website, has not been verified by the BBC but experts who follow the court closely have said they think it is authentic. Only a handful of people have access to decisions before they become public. And draft opinions can change.