California, which is home to a majority of DACA recipients, is playing a key role in the high court's hearing. State Attorney General Xavier Becerra is scheduled to make his case on behalf of DACA.
President Trump shared his thoughts Tuesday morning, tweeting, "Many of the people in DACA, no longer very young, are far from "angels." Some are very tough, hardened criminals. President Obama said he had no legal right to sign order, but would anyway. If Supreme Court remedies with overturn, a deal will be made with Dems for them to stay!"
There did not appear to be any support among the Supreme Court's five conservatives in extended arguments for blocking the program, which currently protects 660,000 undocumented immigrants who came to the United States as children.
Chief Justice John Roberts and Justice Brett Kavanaugh were among the justices who indicated that the administration has provided sufficient reason for wanting to do away with the program. Justices Neil Gorsuch and Samuel Alito raised questions about whether courts should even be reviewing the executive branch's discretionary decisions.
However, the Supreme Court's decision is not expected until June, at the height of the 2020 presidential campaign.
Some DACA recipients who are part of the lawsuit against Trump's action were in the courtroom for the arguments. Many people camped out in front of the court for days for a chance at some of the few seats available to the general public. Roberts rejected a request to provide live or same-day audio of the arguments. The court will post the audio on its website Friday.
Students at several Southland schools, including East L.A.'s Garfield High School, were participating in walkouts Tuesday morning. In downtown Los Angeles, DACA supporters gathered outside the Edward R. Roybal Federal Building before a planned march to MacArthur Park, the site of a rally beginning at 2 p.m.
"Everyone belongs here. This is our home," a DACA recipient who gave her name only as Leticia told the crowd in emotional remarks. "This is the only home I know."
L.A. County Supervisor Hilda Solis also held a press conference about the issue at the Los Angeles County Hall of Administration.
"We have more DACA recipients than any other county in this country," Solis noted. "We hear them, we embrace them and we believe in them."
A mass was held in support of so-called Dreamers Monday night in North Hollywood.
Jose Flores has lived in L.A. since he was 4. He studied at UC Berkeley and owns a small business with his parents. DACA afforded him immigration status that his parents have never been able to achieve, but regardless of how the court rules, the decision won't change the country he calls home.
"I've always felt like an American so I've acted as it," Flores said. "This is my home. This is my church. I've been coming here for about 20 years or so and my family's here. My life is here."
If the Supreme Court agrees with the Trump administration in the DACA case, Congress could follow up by putting the program on surer legal footing. But the absence of comprehensive immigration reform from Congress is what prompted Obama to create DACA in 2012, giving people two-year renewable reprieves from the threat of deportation while also allowing them to work.
Federal courts struck down an expansion of DACA and the creation of similar protections for undocumented immigrants whose children are U.S. citizens.
Trump's anti-immigrant rhetoric was a key part of his presidential campaign in 2016, and his administration pointed to the invalidation of the expansion and the threat of a lawsuit against DACA by Texas and other Republican-led states as reasons to bring the program to a halt.
Young immigrants, civil rights groups, universities and Democratic-led cities and states sued to block the administration. They persuaded courts in New York, San Francisco and Washington, D.C., that the administration had been "arbitrary and capricious" in its actions, in violation of a federal law that requires policy changes to be done in an orderly way.
The Associated Press contributed to this story.