The document is not a final decision, but a "first draft" of the opinion in a case challenging Mississippi's ban on abortions after 15 weeks.
Chief Justice John Roberts confirmed Tuesday the authenticity of the leaked draft opinion and ordered an investigation into what he called an "egregious breach of trust."
Governor JB Pritzker condemned the report Tuesday that could allow states to enact even more restrictive anti-choice laws that would deny a woman's access to reproductive health care.
"We were warned about today. We were warned over and over and over again, and yet some folks didn't want to believe it. So let me put you on alert again," the governor said. "If this ruling stands -- If they can reverse 50 years of settled law, then every Supreme Court decision that has made this country freer and fairer can be reversed by this court."
The governor made his remarks at the SEIU union hall in Chicago, which was packed with cheering abortion rights advocates waving signs that read "protect choice."
"We are healthcare workers and we know abortion is healthcare," said Erica Bland, SEIU Healthcare. "If we don't have access to safe and legal abortions then women will suffer. Suffer from injuries and infections from unsafe illegal abortions and far too many will die."
Pritzker has made it very clear abortions will remain legal in Illinois regardless of what the Supreme Court decides.
RELATED: Supreme Court leak energizes Democrats and Republicans and their bases in midterm election year
Following the bombshell news Monday night, Pritzker also talked to CNN, saying if this leak is true, this is a disappointing day for women, not just here in Illinois, but across the country.
RELATED: New center will assist people who come to Illinois for abortions with travel, other expenses
"This is a terrible day for our nation and it's a disgraceful decision. It's a scary day for women. In Illinois, we took steps to protect women's reproductive health because we feared that this day would come. And let's be clear after the Supreme Court decision, um, women will still be getting abortions, but in 26 out of 50 states, those abortions will be unsafe and potentially deadly," Pritzker said. "And in my opinion, Republicans should be ashamed of themselves. For a party that says that they're all about individual freedom, they're hell bent on taking away freedoms from so many women. And remember if they come after Roe, they're gonna come after everything."
Early in his term, Pritzker signed the Reproductive Health Act to protect Illinois women in anticipation of a conservative Supreme Court overturning Roe. He also repealed the Parental Notification Act in 2021, which ensures that a pregnant minor can choose whether or not to involve a family member or legal guardian in their decision to have or not have an abortion.
Map shows the Center for Reproductive Rights' abortion access by state
In a South Loop hotel, anti-abortion rights groups March for Life Chicago and Illinois Right to Life gathered for a rally of their own. Having long fought for greater restrictions on abortion and overturning Roe v. Wade, they reacted with joy and excitement to the leak.
ABC7 Legal Analyst Gil Soffer said the decision, if it sticks, could radically change the political and legal landscape of abortion rights.
WATCH: ABC7 Legal Analyst Gil Soffer weighs in on the leaked SCOTUS opinion draft
"It would not mean that abortion becomes criminal across the United States, it means every state can decide for itself whether abortion becomes criminal," he said.
Soffer added that it is "unheard of" for a draft like this from the Supreme Court to be leaked.
Illinois prepared for influx of out-of-state abortion patients if Roe v. Wade overturned
A decision to overturn Roe v. Wade could have rippling impacts on abortion in Illinois and across the country.
Women who have had abortions have been open and emphatic about how important their choice, and legal ability to make that choice, was to their lives.
Betsy Shaack was in her 30s when she had her abortion in the 1990s. Without the choice, she said, the outcome would have been devastating.
"I probably would have possibly taken my own life or put myself in a dangerous position," she said. "I was not meant to be a mother. I was not meant to carry a child. None of that was for me."
Shaack now volunteers for an organization that safely escorts women to abortion clinics. So does Lindsay Cogan, who was in her early 20s when she had her abortion.
"I could barely take care of myself. To think I would be in charge of rearing another person, that is the true crime right there," Cogan said. "From my personal experience, had I not had safe access to abortion I would have probably died trying. I would have done anything not to be pregnant."
According to the CDC, one out of every four women in the United States have had an abortion. Sixty persecent are already mothers, women in their 20s make up close to 57% of all abortions, and at 23.8% Black women have the highest rate compared to white women at 6.6%.
If Roe v. Wade is overturned, abortion will remain legal in Illinois but not in surrounding Midwestern states with restrictive abortion laws and bans. For the past five years, Planned Parenthood Illinois has been preparing for a possible post-Roe world in which women from other states will come here for abortions.
"Illinois could see 20,000 to 30,000 additional abortion patients per year if Roe v. Wade is overturned," said Jennifer Welch, Planned Parenthood of Illinois president and CEO.
To prepare, Planned Parenthood has built more health centers near state lines and have launched telehealth appointments for abortion pills.
"We are really worried about patients who have faced this horrible dilemma and have to travel thousands of miles to a safe haven state like Illinois," Welch said.
Planned Parenthood Illinois said it is in the process of raising $40 million to help women from all states gain access to safe and legal abortions.
Anti-abortion rights activists said they will continue to fight until abortion in illegal in all 50 states.
Local Leaders React To Leaked Abortion Rights Opinion
"No matter what atrocious opinion the Supreme Court officially rolls out this summer in regards to Roe v Wade, abortion is safe and legal in Illinois," Pritzker reassured.
Mayor Lori Lightfoot tweeted she is "enraged."
What we're seeing tonight on Roe v. Wade is a horrendous attack on our fundamental right to choose, and we will fight against it with everything we've got. You have my word: I will do everything I can to guarantee your right to an abortion.— Lori Lightfoot (@LoriLightfoot) May 3, 2022
"Chicago will continue to be a haven for those seeking access to the full range of safe reproductive care. We will also continue to fight in Chicago to protect the right to choose and will not stop fighting to protect us right in our surrounding counties and states," Lightfoot said in a statement.
WATCH: 'I felt a gut punch,' Lightfoot says on leaked abortion opinion
"I don't condone the leaking of internal Supreme Court documents... I don't know who leaked the opinion, or why. But I know that today, [Americans] across this country are grappling with the very real concern, and yes, the fear, that they may lose a critical constitutional right in just a matter of weeks," said U.S. Senate Majority Whip and Chair of the Senate Judiciary Committee Dick Durbin (D-IL). "Everyone-no matter where you live or how much money you make-deserves access to health care without barriers or political roadblocks. Regardless of the Supreme Court's final decision this summer, Congress cannot sit idly by nor can this Committee. We must enshrine into law a woman's right to make her own health care choices."
"Abortion has objectified women, dehumanized the most innocent members of the human family, and made mothers and their children mortal enemies and created a billion-dollar industry that profits from this. Women and their children deserve better," added the executive director of Illinois Right to Life.
Abortion has objectified women, dehumanized the most innocent members of the human family, and made mothers and their children mortal enemies and created a billion-dollar industry that profits from this. Women and their children deserve better, @JBPritzker https://t.co/MM4tbxFt2z— Amy C. Gehrke (@AmyCGehrke1) May 3, 2022
"This is utterly shameful but we can stop it. The Senate MUST end the filibuster and codify Roe," Representative Mike Quigley (D-IL 5th District) tweeted.
Let’s be clear—Republicans stole two Supreme Court seats to make this happen. The party of “small government” wants to control women’s bodies.— Mike Quigley (@RepMikeQuigley) May 3, 2022
This is utterly shameful but we can stop it. The Senate MUST end the filibuster and codify Roe. https://t.co/9nzcwHZaiW
"When we heard the incredible news tonight we dropped to our knees and said a prayer as a family in gratitude for all the lives that will be saved. And then we said the pledge of allegiance. The flag looks different after this ruling - it shines even brighter," said Jesse Sullivan, republican candidate for Illinois governor tweeted.
When we heard the incredible news tonight we dropped to our knees and said a prayer as a family in gratitude for all the lives that will be saved. And then we said the pledge of allegiance. The flag looks different after this ruling - it shines even brighter. 🙏🏻🇺🇸— Jesse Sullivan (@JesseSullivanIL) May 3, 2022
WATCH: ABC7 political analyst talks about how Roe V Wade decision could impact Illinois governor's race
"The leaked SCOTUS opinion on Roe v Wade will set women's rights back generations. Black women & those living in rural areas will be worst impacted. We must codify the right to safe abortions," said Representative Robin Kelly (D-IL 2nd District).
The leaked SCOTUS opinion on Roe v Wade will set women’s rights back generations. Black women & those living in rural areas will be worst impacted.— Robin Kelly (@RepRobinKelly) May 3, 2022
We must codify the right to safe abortions.
"As a Pro-Life lawmaker, I've long advocated for an end to the 'Roe' decision. It was wrong from the beginning, and I hope the Court's pending decision empowers states to enact pro-Life laws and protect the unborn," Representative Rodney Davis (R-IL 13th District) said in part in a statement.
"This is a war on women, and it will disproportionately impact marginalized communities. As a former board chair of Planned Parenthood of IL and a woman who has had an abortion, this is deeply personal," said Cook County State's Attorney Kim Foxx.
Extremely disturbing news tonight for women all over the country. I’ll never give up the fight for a woman’s right to choose.— Kwame Raoul (@KwameRaoul) May 3, 2022
"Extremely disturbing news tonight for women all over the country. I'll never give up the fight for a woman's right to choose," tweeted Illinois Attorney General Kwame Raoul.
This is a war on women, and it will disproportionately impact marginalized communities. As a former board chair of Planned Parenthood of IL and a woman who has had an abortion, this is deeply personal. https://t.co/2W00jK9JZ8— Kim Foxx (@KimFoxx) May 3, 2022
The Democratic Party of Illinois said: "Illinois Democrats have made significant progress in expanding women's reproductive rights in our state, but clearly this fight is long from over. We will continue to do everything in our power to protect the right to choose from Illinois Republicans dead-set on following the extremist playbook from their colleagues in states like Missouri, Kentucky, and Texas...To those who feel under attack right now, know that you are not alone. Illinois Democrats at every level will never stop fighting to protect your rights, your healthcare, and your voice. Never."
Planned Parenthood of Illinois released a statement on the leaked document, saying:
"Planned Parenthood of Illinois is furious that the Supreme Court is prepared to ignore half a century of settled law and end the constitutional right to an abortion by overturning Roe v. Wade. But it's also not a surprise. We have been preparing for this decision for years, and we will continue to ensure that every patient, no matter where they live, has access to the health care they need and deserve.
We are proud to say that abortion is still safe and legal in Illinois.
This is a devastating blow for the millions of people who will suddenly find themselves in an abortion desert; facing a daunting dilemma - travel hundreds of miles to access an abortion, seek an illegal alternative or carry a pregnancy to term against their will. We will continue to fight so that everyone can access the fundamental reproductive health care they need and deserve - no matter what."
President Joe Biden also issued a statement in response to the leak of an apparent draft Supreme Court opinion showing that the panel's conservative majority is ready to overturn nearly 50 years of established abortion rights.
He said his administration will work to codify abortion right into law.
"I believe that a woman's right to choose is fundamental, Roe has been the law of the land for almost fifty years, and basic fairness and the stability of our law demand that it not be overturned," the statement read.