A British court is set to make a final decision on Monday on whether Julian Assange, the WikiLeaks founder, will be granted the right to appeal an extradition order to the United States, where he faces charges under the Espionage Act.

Mr. Assange has been held in a London prison since 2019, accused by the United States of violations in connection with obtaining and publishing classified government documents on WikiLeaks in 2010.

His case has slowly wound through the courts since his extradition was ordered by a London court in April 2022. Priti Patel, Britain’s home secretary at the time, approved the extradition two months later.

In February, the High Court heard Mr. Assange’s final bid for an appeal, and in March, the judges asked the U.S. authorities to provide specific assurances about his treatment if extradited.

In a hearing on Monday, the court will rule on whether those assurances — that Mr. Assange would not face the death penalty or be persecuted for his nationality and that he could seek the same First Amendment protections as a U.S. citizen — are satisfactory, and whether Mr. Assange can appeal his extradition.

While the timing for the judgment is still unclear, it could come as early as Monday afternoon, after the hearing ends. Here are the possible outcomes:

Mr. Assange’s appeal request is denied.

In a news briefing held last week, members of Mr. Assange’s legal team and his wife said that he could be put on a plane bound for the United States within 24 hours if the court ruled that he cannot appeal, potentially ending his yearslong battle.

But Mr. Assange’s legal team has vowed to challenge his extradition by appealing to the European Court of Human Rights in Strasbourg, France. Britain is compelled to comply with the court’s judgment as a member of the court and a signatory to the European Convention on Human Rights. A challenge in the court could potentially pause his extradition until the case is heard in Strasbourg.

If the E.C.H.R. does not intervene, Mr. Assange could be extradited to face charges in the United States, including 17 counts of violating the Espionage Act, for his role in obtaining and publishing secret military and diplomatic documents, and a federal charge of conspiring to hack into a Pentagon computer network.

If convicted on the charges, he could face a sentence of up to 175 years in prison, according to his lawyers, who have described the accusations as politically motivated. But lawyers for the U.S. government, which has said that the leaks put lives at risk, have said that Mr. Assange would be more likely to receive a shorter sentence of four to six years.

Mr. Assange is allowed to appeal.

In its March ruling, the court denied Mr. Assange’s requests to appeal on six of the nine grounds he raised, saying that they did “not have any merit.” But they said that Mr. Assange had “an arguable case” on the remaining three grounds for appeal: that in the United States he could face the death penalty, be persecuted for his nationality or not have access to First Amendment protections.

If the court determines that the assurances it has received from the United States on these three issues are not sufficient, an appeal could go forward, which could open the door to a new decision about his extradition.

This would mean that the legal case, which has caught the world’s attention and mobilized defenders of press freedom, will continue to be disputed, and that Mr. Assange’s removal to the United States will at least be delayed.

There could be a political agreement.

Mr. Assange’s legal team said last week that it was continuing to push for a political resolution to his extradition, in the hope that he might ultimately be allowed to return to Australia, his home country.

Jennifer Robinson, a human rights lawyer, said the team was working closely with the Australian prime minister and attorney general “to try to seek a resolution of this case.”

“This could be resolved at any time when the United States makes the decision, which we say is the right one, to drop this case and to drop an indictment that has been universally condemned by free speech groups,” she said.

Last month, President Biden said that the administration was considering a request from Australia that Mr. Assange be allowed to return there, prompting speculation that the United States could be rethinking his case. The Justice Department declined to comment at the time.

Mr. Assange’s team suggested that the judges could also exercise their judicial discretion and decide to dismiss the extradition case entirely, but there is no indication that this is on the table.

“I have a sense that anything could happen at this stage,” said Stella Assange, Mr. Assange’s wife.