Activists gather Jan. 11 in front of the White House to protest the continuing use of Guantanamo Bay to detain prisoners without trial. Protesters initially gathered at Lafayette Square and marched with a police escort to the Supreme Court. (Jahi Chikwendiu/WASHINGTON POST)

A somber line of protesters wearing orange jumpsuits and black hoods led a group of hundreds of human rights activists on a march from the White House to the Supreme Court to mark the 10th anniversary of the opening of the U.S. military prison at Guantanamo Bay, Cuba.

The march was one of several demonstrations around the world demanding the closure of the controversial detention center, and organizers of Wednesday’s protest say they had about 700 participants, making it the largest such rally since Guantanamo Bay admitted its first detainees in early 2002.

Many human rights activists have been disappointed that President Obama has not closed the prison as promised. The Obama administration contends that Congress has blocked the transfer of some detainees.

The protesters said everyone on Capitol Hill is to blame. The march, which included a walk past the Capitol, symbolized that all three branches of government are responsible, the organizers said.

In a rallying speech at Lafayette Square before the event, Tom Parker, policy director for terrorism, counterterrorism and human rights at Amnesty International, compared the political landscape in Washington to “a little shop of horrors.”

Activists worry that detention provisions in the 2011 National Defense Authorization Act could increase the number of detainees at Guantanamo Bay.

“What we wanted to do is just remind people these prisoners are still detained and there could be more on the way,” Parker said in an interview. “President Obama has failed to keep his promise. More people should be upset by this, more should be here.”

Still, organizers said they were pleased with the turnout on a cold, rainy day. After assembling at Lafayette Square and walking across the street to the White House fence, protesters began a nearly hour-long march to the Supreme Court.

A line of 171 people — wearing the jumpsuits and hoods — symbolized the number of detainees who are still at Guantanamo Bay. They remained quiet, but a throng of demonstrators that followed was decidedly vocal. Call-and-response chants demanded what they said would be justice.

Omar Farah, 35, took the train from his home in New York to participate in the event. He carried a sign that read “Free Djamel,” a reference to detainee Djamel Ameziane. The Algerian was one of the first detainees to be moved to the facility.

Farah, a lawyer, said the protest was an important way to give the detainees an identity.

“Most people don’t know who these people are,” he said. “Part of this protest is getting their names out there, helping people to realize that it’s been 10 years for specific people.”

The detention center was opened in 2002 by the George W. Bush administration as a place to house terrorism suspects after the Sept. 11, 2001, attacks. The facility once held 779 detainees.

Like Farah, many of the protesters were affiliated with legal or human rights advocacy organizations. Four groups served as the primary sponsors for the event: Amnesty International USA, Center for Constitutional Rights, National Religious Campaign Against Torture and Witness Against Torture.

Most of the organizations involved encouraged lead-up activities to hype the march. One protester in an orange jumpsuit and hood sat in a cage in front of the White House grounds as part of a planned 92-hour vigil.

Before dropping a black hood over her face, activist Ellen Barfield of Baltimore said she was on the ninth day of a 10-day fast in honor of Guantanamo Bay detainees. She is a member of Witness Against Torture, which encouraged its members to “hunger for justice” leading up to the protest.

“Right now you can only leave Guantanamo in a coffin,” Barfield said. “So we’ve got to put an end to that, we’ve got to speak out. This is my way, this is our way.”