A US Supreme Court shifted to the right by Donald Trump is to hear a case this week that may roll back 50 years of abortion rights.

On Wednesday, the nation's highest court is to examine a Mississippi law that prohibits most abortions after 15 weeks of pregnancy.

In a landmark 1973 decision, Roe v. Wade, the court held that access to abortion is a woman's constitutional right, striking down state laws that restricted the procedure.

In a 1992 ruling, Planned Parenthood v. Casey, the court guaranteed a woman's right to an abortion until the fetus is viable outside the womb, which is typically around 22 to 24 weeks.

The Supreme Court's rulings did not put an end, however, to conservative and religious opposition to abortion, and anti-abortion activists believe their moment may have finally arrived after years of political and legal battles.

"Roe's Waterloo is, finally, at hand," conservative commentator Hugh Hewitt wrote in The Washington Post.

The anti-abortion group March for Life said the importance of the Mississippi case "cannot be underestimated."

"We hope and pray this Supreme Court decision could be a historic turning point for the protection of the most vulnerable," it said.

The 2018 Mississippi law bans abortion after 15 weeks of pregnancy and makes no exception for rape or incest.

It was blocked as unconstitutional by lower courts before ending up in the Supreme Court.

Just by agreeing to hear the case, the court indicated that it was prepared to revisit its previous rulings, at least when it comes to the question of "viability."

Mississippi, a conservative Bible Belt state, is asking the top court to go even further and strike down Roe v. Wade.

"Nothing in constitutional text, structure, history, or tradition supports a right to abortion," the state argued in a brief submitted to the court.

'In disbelief'

Mississippi has received the backing of 18 other Republican-led states, hundreds of lawmakers, the Catholic Church and anti-abortion groups, some of which have spent millions of dollars on publicity campaigns.

They have been galvanized by Trump's nomination to the court of three justices, giving conservatives a 6-3 majority.

Two of the justices who were nominated by Trump replaced justices who were defenders of women's abortion rights -- Anthony Kennedy, whose seat went to Brett Kavanaugh, and feminist icon Ruth Bader Ginsburg, whose successor, Amy Coney Barrett, is a devout Catholic.

The impact of the new justices on the panel was apparent on September 1 when the court declined a request to block a Texas law that bans abortion after six weeks of pregnancy.

The court later held an emergency hearing on the Texas law but has yet to render a decision.

Shannon Brewer, director of the only clinic providing abortions in Mississippi, said she is the most worried she has even been.

"I am still at the point where I'm in disbelief that the Supreme Court would even take this case," Brewer said. "That tells me a lot about the direction that we're going in."

Her Jackson Women's Health Clinic had previously stopped providing abortions to women who are more than 16 weeks pregnant due to increasing restrictions.

Julie Rikelman, a lawyer for the Center for Reproductive Rights who will argue the case before the court, said that if the justices uphold the Mississippi law "it would be possible for states to ban abortion at virtually any point in pregnancy."

"If the court upholds the ban, which everyone agrees is two months before viability, it is overruling Roe and Casey even if the decision doesn't use those words," Rikelman said.

Anti-abortion activists are not the only ones mobilizing.

Medical associations, women's rights and civil rights groups and others have submitted briefs to the court along with hundreds of Democratic lawmakers and some 500 top athletes including soccer star Megan Rapinoe.

"Forcing a woman to continue a pregnancy against her will is a profound intrusion on her autonomy, her bodily integrity, and her equal standing in society," the Department of Justice said in a brief to the court.

The justices will have until June to render a decision.