Hundreds of demonstrators have staged a roadblock outside The Royal Courts of Justice in opposition to the Government's proposed changes to legal aid.
Supporters of anti-cuts direct action group UK Uncut gathered on the Strand in central London at around midday.
Many of them sat on the road and others put their bicycles in the way of traffic.
They held placards which read: "Justice for all, not just the rich".
City of London Police warned the group that they were stopping the emergency services from travelling around the capital.
The demonstration was one of several roadblocks planned in towns and cities across the UK, including Manchester, Liverpool, Cambridge, Hull, Northampton and Norwich.
The protesters in London held a mock trial for Justice Secretary Chris Grayling, and attached a banner to the fence of the court building which warned: "No justice, no peace".
A number of police officers were at the scene but they were not attempting to force the group to clear the road.
The westbound lane was reopened shortly before 2pm as the demonstration was contained to a smaller area.
UK Uncut spokesman David Conway, 25, from south London, said: "The Government's plans will block access to justice for millions of people.
"We're blocking roads to make a stand against that and to make it clear how strongly people around the country oppose these outrageous plans."
He added: "These plans will cost as much as five times more than they'll save.
"People will have to represent themselves in court and get compensation much later than they should."
A Ministry of Justice spokesman said: "We have one of the best legal professions in the world, but cannot close our eyes to the fact that - at around £2 billion - legal aid is costing too much.
"The Government's legal aid reforms will create a sustainable legal aid system that will still be one of the most generous in the world. We want to ensure the limited public funds available are targeted at those cases and people who need it most.
"At a time when major financial challenges are being felt by businesses and households across the country, the legal sector cannot be immune from the Government's commitment to getting better value for every penny of taxpayers' money we spend."