On Wednesday, the Supreme Court will reconsider the fundamental principle that has underpinned abortion law since the 1973 Roe v. Wade ruling: the right to end a pregnancy before the viability of the fetus.

Oral arguments will take place in Dobbs v. Jackson Women’s Health Organization, a case concerning Mississippi’s abortion ban after 15 weeks of pregnancy. The law was designed as a direct challenge to Roe, and the Supreme Court has accepted a question the state wants answered in its ruling: “Whether all pre-viability prohibitions on elective abortions are unconstitutional.”

To understand the vulnerability of Roe v. Wade, one needs to dig into the backstory of how the case was decided almost 50 years ago. And when it comes to the viability standard, all roads lead to Larry Hammond, Justice Lewis Powell’s law clerk at the time.

Hammond’s bench memo to Powell in October 1972 is arguably the most important ever produced by a Supreme Court law clerk.

Clerks typically draft dry bench memos to justices outlining the facts and arguments to consider. But Hammond’s memo was the very source of the concept of viability in Roe.

The notion of using viability — the time when a fetus can survive outside the womb — had not even been argued by the litigants. It was Hammond’s suggestion.

Hammond died in March 2020 at 74 of complications from a lung disease. In 2013, I interviewed him for my book “January 1973: Watergate, Roe v. Wade, Vietnam, and the Month That Changed America Forever.” It was the only extensive interview he ever gave on his behind-the-scenes work in the Roe case.

“Before he died, Justice Powell released me to speak about our interactions so long as I didn’t talk about other justices,” he told me. Our conversation clarified the decision-making process that underpins the legal precedent now coming under question.

Hammond was born in El Paso to Episcopalian parents with strong religious convictions. After law school at the University of Texas, he won a clerkship on the U. S. Court of Appeals in Washington and subsequently was hired by Justice Hugo Black in the summer of 1971.

Black was 85, and he suffered a series of strokes that resulted in his death in September 1971. Hammond was a clerk without a justice; he was reduced to shepherding schoolchildren on Supreme Court tours, playing basketball at the court’s facility and whiling away afternoons in gab sessions with Justice Thurgood Marshall.

By tradition, he should have been done at the end of the court’s term, but fate intervened. President Richard Nixon nominated Virginia attorney Lewis Powell to replace Black, and Powell decided to retain Hammond. Their partnership was immediate. Powell would write to Hammond when he completed his clerkship: “I think you are one of the ablest lawyers with whom I have ever worked. Your capacity of penetrating legal analysis is exceptional.”

Meanwhile, two abortion cases had found their way to the Supreme Court: Roe v. Wade, based on a strict, century-old Texas statute, and Doe v. Bolton, concerning a less restrictive law out of Georgia. The cases were argued in December 1971, just before Powell and William Rehnquist were confirmed by the Senate and installed on the court. Sarah Weddington, then 26 and a former law school classmate of Hammond, argued for the woman then known only as Jane Roe. By court tradition, since Powell and Rehnquist did not sit for oral argument, they were precluded from taking part in deciding the cases.

Chief Justice Warren Burger assigned Justice Harry Blackmun to draft the opinions in both abortion cases. Blackmun had served as counsel to the Mayo Clinic in his days practicing law in Minnesota, so Burger thought he was a natural to address what he saw as a medical issue. Justice William O. Douglas was unhappy, believing he had the right to author the opinions, having drafted the majority opinion in a groundbreaking right-to-privacy contraception case a few years earlier.

Blackmun took his time, studying medical textbooks on his own. His first efforts were circulated in late May 1972. In his draft opinion, Blackmun disposed of the Texas statute on vagueness grounds but took on the substantive right of a woman to decide to terminate her pregnancy when analyzing the Georgia statute. While Blackmun recognized the right to an abortion, he wrote that the court could not, “at this point in the development of man’s knowledge,” specify “when life begins.” So he drew no line in the pregnancy after which abortions could be prohibited.

This draft, had it become law, would have left a vastly different political landscape from the one we find ourselves in now. The case would have allowed states to freely establish their own abortion limits, a process that was already underway in 1972. Perhaps later the court would have drawn a firmer line, or maybe states would have each come up with their own solutions deemed acceptable to a majority of their residents.

Future justices as ideologically divergent as Ruth Bader Ginsburg and Antonin Scalia later agreed that this gradual solution would have been preferable to the national divisiveness that followed the broad sweep of Roe.

But in June 1972, Burger, worried that such an important ruling would be handed down by a partial court, sought to reargue the cases with Powell and Rehnquist participating. Douglas vehemently disagreed, believing that enough of the justices had approved of Blackmun’s drafts, which incorporated Douglas’s right-to-privacy argument. He penned a rarely noted dissent to reargument that was never formally filed (it was discovered later in court files), writing, “Opinions in the two cases have been circulated, and each commands the votes of five members of [a seven-member] Court. The decisions should therefore be announced.”

But Douglas lost the argument. With Powell now able to review the drafts, he asked Hammond to take the summer to study the file. Hammond did so and wrote a memo recommending that Powell, too, agree to a woman’s right to an abortion. To Hammond’s shock, when Powell returned at the end of the summer, the conservative justice said he agreed with Hammond’s analysis.

The reargument followed in a hearing in October 1972, during which no one mentioned the term “viability.” Blackmun’s next draft elevated Roe v. Wade to the lead case, and now he was ready to draw a line. This time, his draft opinion fixed the point before which states could not outlaw abortions at “the end of the first trimester.”

The problem, Hammond thought, was that there was no logic to the first trimester limit. What about young women who might not realize or come to terms with their pregnancy before that point? “For many poor, or frightened, or uneducated, or unsophisticated girls,” Hammond wrote to Powell, “the decision to seek help may not occur during the first 12 weeks.”

This led Hammond to point Powell back to his bench memo, written before the second oral argument. In it, Hammond argued that the Supreme Court should not be in the line-drawing business, but if it did find it necessary to do so, viability seemed the most rational point where common agreement on the court could be mustered. Based on a newly decided lower-court case out of Connecticut, Hammond reasoned that the state’s interest in protecting potential fetal life “becomes more dominant when the fetus is capable of independent existence (or becomes ‘viable’).”

The movement of the line from three months to six months, essentially the end of the second trimester, was a critical development, especially considering the lack of any expert testimony or lawyer argument supporting this cutoff point.

Nonetheless, Powell, through private correspondence, persuaded Blackmun to go along with viability. When the Roe v. Wade ruling was handed down in January 1973, it contained a trimester analysis that disallowed state abortion bans prior to viability.

While the reaction was initially muted, with the exception of vocal opposition from the Catholic Church, the sweeping pronouncement in Roe v. Wade soon generated a vast antiabortion movement. As medical understanding of fetal development has sharpened (the early start of a heartbeat, the moment when a fetus might feel pain), the viability standard has come under intense pressure.

In the months leading up to the announcement of the opinions in Roe and Doe, the Supreme Court twice considered draft opinions that would have led the nation in a different direction. History probably would have changed had the court adopted Blackmun’s first suggestion that the court draw no line as to “when life begins,” or had it accepted his second approach of cutting off abortions after the first trimester.

But now, with the Mississippi case, we will learn whether the court affirms the continuing use of “viability” as the limit on regulation of abortion or overturns it following a long religious and conservative crusade against Roe v. Wade.

When Hammond died, he was deeply mourned in his Phoenix community, nationally, and by those who worked with him. He was the founder of the Arizona Justice Project, the country’s fifth organization dedicated to exonerating the wrongly convicted, where he served as president for 22 years.

But he stayed out of the abortion debate. Following his clerkship, he had argued about abortion with future Supreme Court Justice Antonin Scalia at Notre Dame Law School and found it distasteful. “I decided I should plow other fields,” he told me.

His role in changing history is not found in any obituary, nor was it mentioned in his glowing and lengthy Zoom memorial service. But his quiet push for the viability standard will once again be front and center in the Supreme Court’s decision-making over abortion.

James D. Robenalt is a lawyer and author of four nonfiction books, including “January 1973, Watergate, Roe v. Wade, Vietnam, and the Month That Changed America Forever.”