It’s the protection against torture, slavery and unfair trials that the UK helped write in the wake of the Second World War.
So it’s striking that only today, two Tory leadership candidates became the first to rule out leaving the European Convention on Human Rights.
Penny Mordaunt and Tom Tugendhat were both asked by the BBC if they would take the UK out of the ECHR, and replied: “No”.
The other three candidates - Rishi Sunak, Liz Truss and Kemi Badenoch - have been a lot harder to pin down.
And Ms Truss told a behind-closed-doors hustings of Tory MPs that she would consider leaving the ECHR as a last resort.
Conservative politicians have launched renewed attacks on the Convention after it hit plans to deport asylum seekers to Rwanda.
The European Court of Human Rights, which enforces the Convention, grounded a deportation flight until a full High Court hearing could be held later this year.
That led right-winger Suella Braverman, who’s since been knocked out of the race, to promise to leave the ECHR.
All five remaining Tory leadership candidates support deporting asylum seekers to Rwanda, but they differ on the ECHR.
Below we look at what the European Convention on Human Rights is - and where all the candidates stand.
What is the European Convention on Human Rights?
The UK helped set up the European Convention on Human Rights in the aftermath of the Second World War.
Winston Churchill was instrumental in shaping the 1950 pact, agreed in Rome.
But it was only enshrined in UK law 48 years later when Tony Blair ’s Labour Government passed the 1998 Human Rights Act.
Some Brexit-backers voting in 2016 believed quitting the EU would stop the reach of all European judges into British life.
But leaving the bloc only ended the role of the European Court of Justice.
The Strasbourg-based European Court of Human Rights, which enforces the Convention, is separate from the EU - and the UK’s membership was not affected by Brexit .
Tory governments have long pledged to produce a British Bill of Rights which would supersede or at least work alongside the ECHR.
Yet such a move could pile further pressure on the fragile peace in Northern Ireland.
The ECHR is a key plank of the 1998 Good Friday Agreement peace deal in the province.
As part of the pact, the British Government committed to incorporating the ECHR in Northern Ireland law.
Overriding it could further strain tensions between Unionists and Republicans in that corner of the UK.
Where the Tory leadership candidates stand on the ECHR
TOM TUGENDHAT: The Tory leadership contender was asked by the BBC: “Would you leave the ECHR?” He replied: “No.”
PENNY MORDAUNT: Asked by the BBC if she would “withdraw the UK from the ECHR” she replied: “No.”
KEMI BADENOCH: We have asked her team repeatedly whether she would leave the ECHR, but not received a response.
LIZ TRUSS: In a hustings with Tory MPs, she backed leaving the European Convention on Human Rights as a last resort. According to the Sun, she told MPs “if necessary" Britain could rescind its membership - adding: "The ECHR has had mission creep. We have to deal with that." She insisted she wants to reform first, she added: "but if it did take leaving the ECHR I would be prepared to do that."
RISHI SUNAK: Before quitting as Chancellor, he refused to rule out leaving the ECHR. He told ITV News: “It’s right that obviously all options are on the table but we’re clearly not at that point and there’s a lot of work for us to work through.” We have asked his team repeatedly whether he would leave the ECHR if he became PM, but not received a response.
