Rosario Dawson, the actor and celebrity surrogate for Bernie Sanders, was among dozens of people arrested on Capitol Hill on Friday after a week of pro-democracy demonstrations at the heart of the US government.

The actor was briefly detained for processing by police in Washington and will be required to pay a $50 fine, but does not face a court appearance or imprisonment. More than 800 people have been arrested for staging sit-ins on the steps of Congress during five days of protests by a movement known as Democracy Spring.

Wearing an American flag, a black jacket with Sanders’ image and various Sanders badges, Dawson said afterwards that US Capitol police gave her multiple warnings before making the arrest, perhaps because they realised the publicity it would generate. “I wanted personally to be in solidarity with the other folks who put themselves on the line and really just to bring attention to this because I think that’s just vitally important,” she explained.

“The police were really great with us, really lovely. I have to say that is not the case for so many people: Dreamers, Black Lives Matter activists, so many people are not seeing this kind of courageousness ... I hope that officers across the nation can take heed of that and recognise that the peaceful protests that are going around the nation should also be treated in the same way as we are being treated today.”

Democracy Spring argues that elections are dominated by special interests and the activists are pushing for Congress to drop laws that would make it more difficult to vote and overturn supreme court decisions such Citizens United, which they say enhanced the role of big money in politics. Although the campaign echoes some of the themes articulated by Sanders and Donald Trump, it claims to be bipartisan with conservatives marching alongside Black Lives Matters members.

Dawson, who has made numerous stump speeches for Sanders, said: “We’re putting ourselves on the line for what a lot of people across America and I think across the planet really want to be able to see happen in America, which is one person, one vote, and to really take the money out of politics so that we can have fair elections where ... we can have true options for our leadership, which we have not been able to see.”

Kai Newkirk, campaign director of Democracy Spring, was arrested at the same time and, walking back to applauding supporters, commented: “We’re not free until we get our democracy back.”

He continued: “It’s historic in terms of the number of people arrested here, sending a message that the American people are fed up with this corruption and inequality in our democracy and we’re demanding that Congress do something to end it now. And if they don’t, we’re going to continue to come back and send a message that those who defend this corrupt status quo will pay a political price. The American people are not going to accept this any more.

“The vast majority of the American people agree with us across the political spectrum. We’re bringing their voice here into the Capitol and Congress is refusing to listen and instead of that is sending people to jail day after day. That’s a scandal, that’s an outrage, and it’s a story that needs to be told.”

Democracy Spring’s activities have included a 140-mile march from Philadelphia to Washington involving people from 33 states. On Friday, 12 protesters handcuffed themselves to scaffolding inside the Capitol rotunda and were arrested. They said in unison: “We the people demand a democracy free from the corruption influence of big money and voter suppression. We demand a democracy where every vote is counted and every voice is heard.”

Many demonstrators are sleeping in churches and obtained a permit to set up a nearby tent outside Union Station, where on Friday a bicycle, compost bin and numerous chairs and political placards were spread ad hoc on the grass. Volunteers kept an eye on people’s bags, a handwritten cardboard sign pointed to lost property, and apples, carrots and other food were available for breakfast or people fresh from jail. One man played guitar while another, with a beard and long hair, sat at a laptop bearing the sticker “Billionaires can’t buy Bernie” running off a noisy power generator.

Christopher Reed, 22, from Morgantown, West Virginia, was among around 400 people arrested on Monday, some of whom were held in jail or a warehouse until after midnight. “I have never felt more like an American than I did that day on the steps, risking arrest so I could make a statement,” he said. “We are planting the seeds of a movement.”

Most demonstrators reported that police had treated them respectfully and some had even expressed support for their cause. Adrian Griffin, 19, a dishwasher from Fayetteville, Arkansas, said: “If you cooperate with the police, they are very professional. They’re not your friend but they’re not your enemy either.”

US Capitol police said on Friday they arrested 12 individuals in the Capitol rotunda and around 130 on the east front plaza for “unlawful demonstration activity”. Eva Malecki, a spokesperson, said: “The demonstrations have been orderly and respectful.”