Megan Ellyia Green knew she was going to be arrested when she walked into the Wainwright Building on Thursday.

With the future of Missouri’s only abortion provider in question, the St Louis alderman and others blocked the elevators of the downtown government building for several hours in an act of civil disobedience in protest of state governor Mike Parson’s attitude to women’s reproductive rights. When police asked them to leave, the protesters refused.

“We said, ‘You’re going to have to remove us,’” Green recalled to the Guardian later. “‘We’re not going to move on our own.’”

Green and other protesters, including local Planned Parenthood board members, were taken into police custody as Missouri’s last remaining abortion provider – a Planned Parenthood in St Louis – could lose its license on Friday, which would make it the first state in the country where women would not have access to legal abortions since the landmark Roe v Wade decision secured abortion rights nationwide in 1973.

The state claims that the healthcare provider would not comply with an investigation by the department of health and senior services and declined to renew its license. But Planned Parenthood has sued, arguing the state government is “abusing its power” and using the DHSS as a “weapon” to undercut women’s rights.

A judge is set to rule some time on Friday on the organization’s right to provide the service.

“This is a dark day,” Dr David Eisenberg, co-medical director of the Planned Parenthood of the St Louis region, said Thursday. “There is no way I imagined we’d be in this position.”

Planned Parenthood’s license is due to expire at midnight – unless circuit judge Michael Steltzer rules in favor of the healthcare organization, allowing it to continue providing abortions. If Steltzer sides with Parson and the DHSS director, Randall Williams, it would represent an enormous win for the anti-abortion movement, which has gained traction across the United States in recent months.

A number of states, including Missouri, have recently passed extremely restrictive anti-abortion bills. Alabama has passed the most draconian; the state this month approved a near total ban on abortion, including in cases of rape and incest, with the sole exception of cases in which the mother’s life is in “serious risk”.

Missouri passed its own severe abortion law shortly thereafter: Parson and the Republican legislature this month approved a bill banning abortions after eight weeks and even imposing criminal sentences on doctors who perform the procedure. The legislation could eventually make its way to the supreme court in a challenge against Roe v Wade.

But the action against the St Louis Planned Parenthood clinic represents a different kind of threat to abortion rights – one undertaken not through the legislature, but through administrative maneuvering.

“Everything we fought for, all the progress we made – this is putting women at risk,” Linda Zavove, co-president of Women’s Voices Raised for Social Justice, a St Louis-based education and advocacy organization, said in an interview. “It’s a scary situation to think we’re going backward.”

It’s not clear how Steltzer will rule.

The judge heard arguments from the state and abortion rights advocates Thursday as protesters rallied in St Louis.

Zavove participated in the demonstration, rallying against Parson for using “department regulation and licensing as a form of harassment” to undermine women’s reproductive rights.

“I hope it sends the message that we are going to be very active in the political process,” said Zavove, the healthcare liaison for Women’s Voices Raised for Social Justice.

Meanwhile, Eisenberg continued to see patients. He’s been doing his job for about a decade, and always loved it. “Some patients come to me in crisis,” he said. “I can fix their crisis. It’s really rewarding.”

But the last couple of days have been different. His clinic may no longer be able to provide a basic, essential healthcare service to women in St Louis, Missouri, and beyond – and he could not assure his patients that he would be able to help them in his state beyond the end of the week.

“I couldn’t tell them for sure, ‘I can help you,’” he said “It feels horrific.”

If Missouri goes dark, more than a million women will no longer have access to abortion care in the state they live in Dr Leana Wen

Missouri’s health department told Planned Parenthood on 20 May that it would not renew its license if it did not address three matters related to its services. The organization agreed to changes in state-mandated counseling and pelvic exams for abortion patients, but said it could not offer up interviews with affiliated physicians as part of the state’s investigation into supposed “deficient practices” by the facility.

But that, according to women’s rights advocates, was merely an excuse to strip access to abortion.

“If Missouri goes dark, more than a million women of reproductive age will no longer have access to abortion care in the state they live in,” Dr Leana Wen, president of the Planned Parenthood action fund, wrote on Twitter on Thursday. “We will not stand for this.”

Protesters converged on St Louis on Thursday, in the shadow of the city’s famous arch, to demonstrate against the measure. For Green, the city’s 15th ward alderman, and others, it was about taking a stand for Missouri – and for women across the nation.

“We’re a test case right now,” Green said, after she’d been released from police custody. “If they are successful here, we will see this strategy replicated across the country.”

“It’s a very scary moment.”