From the moment President Joe Biden promised to nominate a Black woman to the Supreme Court, Judge Ketanji Brown Jackson has been the likeliest pick. And that is who he nominated on Friday to fill retiring Justice Stephen Breyer's seat. 

Here's why and what you need to know about her.

- She's got a background made for a Supreme Court nominee: Jackson up in Miami, her mom a public teacher and her father a lawyer for the school board. One of her uncles was the city's police chief.

She was a high school debate champion, graduated from Harvard Law, where she was an editor on the prestigious Harvard Law Review.

She's been a federal judge for nine years, and last year got on one of the most prestigious federal courts: the U.S. Court of Appeals for the D.C. Circuit. That appeals court is widely seen as a waiting bench for likely Supreme Court candidates.

Before that, she was a public defender and clerk for Breyer.

Jackson is married, with two daughters. She's 51 and would be one of the younger justices. (Breyer, the oldest, is 83. Amy Coney Barrett, the youngest, is 50.)

- She's won over the support of some Republicans in the past: Three Senate Republicans voted to confirm her to the seat she has now on the D.C. circuit court - a not-insignificant number these days. They were Lindsey Graham of South Carolina, Susan Collins of Maine and Lisa Murkowski of Alaska.

"I think she's qualified for the job. She has a different philosophy than I do," Graham told reporters at the time.

When she was being confirmed for her first federal judgeship in 2012, Paul Ryan, who would go on to be the Republican House speaker, introduced her. The two are related by marriage (Ryan's sister-in-law is married to the twin brother of Jackson's husband). Ryan said "although our politics may differ, my praise for Ketanji's intellect, for her character, for her integrity, it is unequivocal."

But it's not clear if any Republicans would support her now. Another potential nominee, J. Michelle Childs, a judge in South Carolina, had at least one Republican senator, Graham, talking favorably about her.

If all 50 Senate Democrats support her, Biden doesn't need any Republican votes to get her nomination confirmed by the Senate. But given how Biden had prioritized bipartisanship, he may like for his nominee to get some Republican votes.

- Liberals really like her: A dozen liberal groups sent a letter to Biden championing Jackson - without mentioning her by name, NBC News reported. They like her background working with some of the most disadvantaged people in the justice system.

Same with civil rights attorney Ben Crump, who has represented the families of prominent victims of police shootings, and wrote that Jackson would represent the Black community well on the court.

By contrast, some labor groups expressed concerns about Childs, who as a lawyer defended some people accused of sexual harassment in the workplace.

- She would be the first public defender on the court: Jackson wouldn't just be making history as the first Black woman to sit on the court. Among the many ways that the Supreme Court lacks diversity is in the judicial careers of its members. No current justice has represented criminal defendants despite the fact the court regularly hears cases where convicted criminals' lives are literally in their hands.

And no justice has held a job, like Jackson, where she represented people accused of a crime who can't afford to pay their own lawyer. (Normally presidents pick people who have experience in the opposite job, as prosecuting those convicted of crimes.) Jackson also served on a commission to lower federal drug sentences in the Obama era.

She and her allies credit her work as a public defender as helping her develop empathy. "There is a direct line from my defender service to what I do on the bench, and I think it's beneficial," she said at her confirmation hearing to sit on the D.C. circuit court.

But that role has also involved getting people off the hook at times. As The Post reported, she kept an attorney convicted of tax fraud out of jail. She successfully defended a man convicted of having an illegal gun in his home. And she worked quite a bit defending prisoners held in Guantánamo Bay, Cuba.

In her confirmation hearing to sit on the D.C. circuit court, Republicans asked her about this. "Have you ever represented a terrorist at Guantánamo Bay?" Sen. Tom Cotton, R-Ark., asked her, the Post reported.

- One of her big decisions was on separation of power in the Trump era: In 2019, Congress was battling with Trump White House Counsel Donald McGahn about whether he should testify to the House Judiciary Committee. The case came before Jackson, who soundly rejected McGahan's arguments. She wrote this well-known line: "[T]he primary takeaway from the past 250 years of recorded American history is that Presidents are not kings."

She did once rule for the Trump administration, allowing his border wall to continue to be built in New Mexico despite the protests of environmental groups.

- She played a key role in getting her uncle out of prison: When Jackson was a public defender in D.C., she received a letter from an uncle asking for her help, The Post reported. He had been sentenced to life in prison under a federal "three strikes" law. Jackson referred him to a high-profile law firm, which took his case pro bono. His sentence was eventually committed by former president Barack Obama, which Jackson took no role in, the Post reported.

- She says she doesn't let race influence her decisions: When asked about race in her confirmation last year, here's what she said: "I'm doing a certain thing when I get my cases. I'm looking at the arguments, the facts and the law. I'm methodically and intentionally setting aside personal views, any other inappropriate considerations, and I would think that race would be the kind of thing that would be inappropriate to inject into my evaluation of a case."

But Jackson has also acknowledged that being a Black woman colors how she sees the world, saying: "I've experienced life in perhaps a different way than some of my colleagues because of who I am, and that might be valuable - I hope it would be valuable - if I was confirmed to the court."