When the Supreme Court decided Roe v. Wade in 1973, establishing a constitutional right to abortion, it noted that it had received 14 friend-of-the-court briefs and listed them in a snug footnote at the beginning of the decision.

By 1992, when the court reaffirmed Roe’s core holding in Planned Parenthood v. Casey, the number of such filings, which lawyers call amicus briefs, had swelled to more than 30, and the footnote reciting them had grown unwieldy, taking up more than a page.

In the decision that overturned Roe in 2022, Dobbs v. Jackson Women’s Health Organization, the court was flooded with more than 140 amicus briefs. The footnote had metastasized, spanning seven pages.

Those 50 years of amicus briefs tell a cumulative story, one explored in a new study published in The Missouri Law Review, “The Rhetoric of Abortion in Amicus Briefs.” Using corpus linguistics, a social-science tool that analyzes patterns of words in large databases, the study found that the briefs “serve as a barometer revealing how various constituencies talk about abortion, women, fetuses, physicians, rights and harms over time.”

The study, conducted by Jamie R. Abrams, a law professor at American University, and Amanda Potts, who teaches at Cardiff University, concluded that opponents of abortion had in some ways been more effective, remaining “resolutely intent on advancing fetal personhood.” The anti-abortion briefs were nimble, they wrote, and were “able to adapt and evolve in response to doctrinal shifts of the court.”

Overall, the authors wrote, abortion opponents had pressed “a more relentlessly human, emotional, personal attack to pursue its political agenda.”