Six states passed laws in 2019 banning abortions once a “fetal heartbeat” is detected, which can be as early as six weeks into pregnancy. While most of these new laws were challenged in court and are temporarily blocked, the trend has continued: another 10 states introduced similar bills in 2019 and more are expected this year.

The sudden success of these measures is not an accident. They are the result of a concerted new strategy by abortion opponents, researchers have found.

Instead of focusing on religious or women’s health concerns, supporters of Georgia’s “heartbeat” bill advanced their arguments by “co-opting the legal successes of progressive movements” such as the civil rights movement and the LGBT rights movement, according to a new study, published in Sexual and Reproductive Health Matters. Throughout the testimony surrounding the bill, Georgia state lawmakers and community members argued that fetuses are a class of persons entitled to protection under the law, just like black Americans and LGBT Americans.

“If you think back to the same sex marriage debate, the state of Massachusetts recognized the franchise of marriage more expansively in Massachusetts than the minimum requirement of federal law,” argued bill sponsor and Georgia State Rep. Ed Setzler in a quote mentioned in the study. “This is walking that same tradition.”

The idea that fetuses deserve rights is not a new concept, but it was once considered a fairly fringe idea. When the first “heartbeat” bill appeared in Ohio in 2011, anti-abortion groups were divided over whether to support it. But since President Donald Trump got elected and tipped the balance of the Supreme Court, abortion opponents have embraced the strategy.

“We were surprised at the references to particular progressive victories, including things like the passage of the 14th Amendment [and] same sex marriage,” says Dabney Evans, an associate professor at Emory University’s Rollins School of Public Health and co-author of the study, which may be the first systematic analysis of the political language around early abortion bans in the United States. She and other researchers examined the testimony and legislative debate advocating for Georgia’s six-week abortion ban last March.

So-called “heartbeat” bills have been controversial in part because they seek to ban abortions at a stage when many women do not yet know they are pregnant, which reproductive rights advocates say means they ban nearly all abortions. Doctors like Dr. Jen Gunter have also noted that, despite the frequently used “heartbeat” language, the cardiac activity measured at six weeks comes from a cluster of cells called the fetal pole rather than from something that looks like a heart.

Evans and her co-author, Subasri Narasimhan, a post-doctoral fellow at Emory’s Center for Reproductive Health Research in the Southeast, noted several examples of legislators and community members “misrepresenting medical science” in their support of the Georgia bill. But the arguments went further, the study says, explaining that the Georgia bill’s supporters were effectively “foreshadowing their legal strategy for a future claim before the U.S. Supreme Court.”

The study outlines three major arguments that the bill’s supporters used to advance their argument. They first asserted that a “heartbeat” was a sign of life and therefore personhood. Then lawmakers and community members said that if fetuses were living, they were a “vulnerable” class of people who deserve rights and protections. And finally, the study explains, the bill’s supporters said that Georgia should be allowed to expand rights and protections to this new group as a matter of states’ rights.

In the Georgia legislature, Setzler, the bill’s sponsor, cited the Dred Scott v. Sanford decision to imply that the Supreme Court had similarly ruled incorrectly in Roe v. Wade. “A 7-2 decision of the U.S. Supreme Court in 1857 said Dred Scott was property, he wasn’t a person,” Setzler said during a committee hearing in March. “The same Supreme Court, by a 7-2 decision, that didn’t recognize Dred Scott, didn’t recognize the humanity of a child in the womb and it’s our opportunity to fix that.”

Another state legislator balked at the comparison and referenced the Three-Fifths compromise as a time when legislators dangerously intervened to decide who was human. But Setzler was undeterred: “Can you help me, through this bill, fully recognize them so it’s not three fifths of a person but a full person?” he asked.

The researchers called these comparisons “false equivalencies,” but added that they add a new dimension to the anti-abortion advocates’ playbook. While previous debates over abortion might have included religious language or restrictions on what providers must do in the name of women’s safety, the study found very little religious rhetoric, and concerns about women’s health were largely brought up by the bill’s opponents.

“In the recent past, anti-abortion advocates have responded by co-opting the language of women’s health and science, focusing most recently on women’s health protection,” the researchers wrote. “While not abandoning this explanatory position, current anti-abortion efforts like HB 481 appear to be layering on a protectionist argument for unborn persons.”

Pro-abortion advocates who fought Georgia’s bill — including those now challenging it in court — have argued that this and other heartbeat bills would actually harm precisely the communities that civil rights laws are designed to protect. An abortion ban, they say, will disproportionately hurt people of color and LGBT people in Georgia who already face barriers to accessing health care.

As is standard practice, the study does not include the names of participants it quotes, but all of the material the researchers analyzed comes from publicly available videos of committee hearings and legislative sessions. TIME reviewed the videos to match Setzler’s quotes with those mentioned in the study.

While Evans and Narasimhan only studied the arguments around Georgia’s abortion ban, they believe their findings will be useful to researchers, community members, activists and legislators in many other states. That’s in large part because many of the “heartbeat” bills being considered around the country are based on model legislation from a group called Faith2Action, which says it provides “the largest network of pro-family organizations.”

“In public health, often people examine the outcomes of policy or legislation, but the process itself is often overlooked,” Narasimhan says. Here, the process is still ongoing as many state legislatures will reconvene this month, and Narasimhan expects other states to make similar arguments to those made in Georgia.

The study also provides a learning opportunity for voters, she added. “This is part of the democracy that we live in,” she says. “This legislative debate is public record. Our analyzing it in this systematized way is bringing forth information into the public record as well and allowing people to hear and see what these debates look like and what tactics are being used for things that will ultimately impact them.”

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Write to Abigail Abrams at abigail.abrams@time.com.