Since 2019, Julian Assange, the founder of WikiLeaks, has been held in a high security prison in southeast London while his lawyers fight a U.S. extradition order. Now, that particular battle may be nearing its end.

On Tuesday, Mr. Assange’s case returned to a British court for a two-day hearing that will determine whether he has exhausted his right to appeal within the U.K. and whether he could be one step closer to being sent to the United States.

Julian Assange leaving Westminster Magistrates Court in London in 2020. A High Court hearing this week will determine whether he has exhausted his right to appeal in the U.K.Credit…Henry Nicholls/Reuters

Mr. Assange did not appear before the court, declining to attend virtually because of ill health, according to his lawyers, but dozens of protesters gathered outside, demanding his release.

In the United States, Assange, 52, faces charges under the Espionage Act of 1917 that could amount to a sentence of up to 175 years in prison, his lawyers say, although lawyers for the United States government had previously said that he was more likely to be sentenced to between four and six years. Here’s what to know about the long-running legal battle over his extradition and what could happen next.

The U.S. charges against Mr. Assange date to events in 2010, when WikiLeaks published tens of thousands of secret military and diplomatic documents leaked by Chelsea Manning, an Army intelligence analyst.