Benedict Cumberbatch is among a group of famous actors standing up for the Human Rights Act, which the government is threatening to scrap and replace with a so-called "British bill of rights".
The Sherlock star, Homeland's David Harewood, Game Of Thrones actress Indira Varma, Vanessa Redgrave and Simon Callow have all appeared in short films based on experiences of people who have relied on the legislation.
Proposals to replace the Act with a British bill of rights are expected to be included in the Queen's Speech today.
Cumberbatch said: "Our Human Rights Act belongs to all of us. It's not for politicians to pick and choose when they apply or who deserves protection.
"Repealing it will mean less protection against state abuse or neglect, and weaken the rights of every single one of us - and the vulnerable most of all."
The acting Labour leader has said that the party fears that "the reality of this Queen's Speech will be very different from the rhetoric".
Harriet Harman warned that "the Queen's Speech will talk of a 'One Nation approach' - yet [David] Cameron sets the nations of the country against each other".
She said: "The real question for this Queen's Speech will be whether it improves our country, our communities and people."
A Labour eurosceptic should lead the "out" campaign at the EU referendum, the party's biggest donor has said.
John Mills, the founder of JML, said that Ukip leader Nigel Farage would put many potential backers off, and suggested ex-minister Kate Hoey as a suitable candidate, as well as Labour backbenchers Graham Stringer and Kelvin Hopkins.
Mr Mills, a vocal critic of Brussels, said that "a successful no campaign has to be a cross-party campaign".
"If it is all the Conservative Party and no Labour then it is never going to gel so it is really important to have key Labour figures in it," he said.
He admitted he would still vote to stay if David Cameron could secure sufficient reforms.
The Queen's Speech is an "early test" of the Conservatives' bona fides on devolving more powers to Holyrood, the SNP's Westminster leader has said.
Angus Robertson said there were "shortcomings" on the draft clauses published earlier this year and he insisted the Scotland Bill - which is due to be published on Thursday - must live up to "both the spirit and the letter" of the cross-party deal that was reached.
He said: "As the First Minister agreed with David Cameron, the Scottish Government will also put forward proposals for a transfer of powers beyond Smith for discussion between the Scottish Secretary and the Deputy First Minister - for which half of Scotland's electorate voted. The people of Scotland have spoken and Westminster has a democratic duty to listen."
The Prime Minister has said that behind today's Queen's Speech is "a clear vision for what our country can be - a country of security and opportunity for everyone".
The speech will set out the new government's legislative agenda, including a measure to ditch income tax for those working a 30-hour week on the minimum wage.
He said: "This is the Queen’s Speech for working people from a One Nation Government that will bring our country together.
"We have a mandate from the British people, a clear manifesto and the instruction to deliver. And we will not waste a single moment in getting on with the task."
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