It's not far off a millennium, it's longer than the Bible says Moses, Isaac and Abraham lived, and most of us might well think that anything that's lasted for 800 years or so was, well, useful.
In 1215, in a field not far from Windsor Castle, a king was forced to sign a document which included among its many clauses several which still hold legal sway in this country.
One of them says this: "No Freeman shall be taken or imprisoned, or be disseised of his Freehold, or Liberties, or free Customs, or be outlawed, or exiled, or any other wise destroyed; nor will We not pass upon him, nor condemn him, but by lawful judgement of his Peers, or by the Law of the land. We will sell to no man, we will not deny or defer to any man either Justice or Right."
That clause is what is known as the right to due process - that everyone on these islands is equal before the law and can be tried by a jury according to the law.
It is a rule which, for 798 years, has stopped the rich and powerful abusing their position, carrying out illegal punishments, acting like dictators or covering up their own crimes. It's quite a useful and good thing.
Of late the woman in charge of our justice system has said she would like to scrap it.
Home Secretary Theresa May wants to tear up the Human Rights Act, a law intended to do no more than make the 1950 European Convention on Human Rights more effective.
You see, after the Second World War when lots of humans were treated like they weren't - Jews, gays, Poles, gypsies - a lot of people thought it was a good idea to make it impossible to do that again.
So we wrote a convention guaranteeing their rights to life, to not be tortured, to not be slaves. It said they had a right to privacy, expression, marriage, freedom of thought and conscience, and a fair trial.
The problem was that if anyone's rights were abused, they had to go to European courts to defend them which was an expensive and long-winded business. So the HRA was introduced so that legal remedies could be quicker and cheaper for us Brits.
Fair enough, right? Except some bits of the HRA were left rather woolly, so that 17 words about everyone having a right to respect for their privacy got abused by, among others, MPs trying to stop you hearing about their expenses, cheating footballers protecting their family-friendly sponsorship deals, and even journalists trying to stop other journalists reporting things.
And if you put into law that people have a right not to be tortured, it makes it tricky to, well, torture them.
Hence why Theresa says: "I'd personally like to see the Human Rights Act go because I think we have had some problems with it.
"I see it, here in the Home Office, particularly, the sort of problems we have in being unable to deport people who perhaps are terrorist suspects. Obviously we've seen it with some foreign criminals who are in the UK."
Now, it's undeniable there are problems with the HRA. It certainly needs a tweak, although you won't hear many lawyers saying that because as a body they've made a mint out of it.
The issue with what Theresa says there is the word 'perhaps'.
People who 'perhaps' are terrorist suspects.
She is referring, if you don't know, to a gentleman of Palestinian extraction called Abu Qatada. Don't get him confused with hook-handed Abu Hamza, or other people who are a bit brown and a bit Muslim and a bit not-too-friendly.
Abu Qatada is a fundamentalist Islamic scholar who fled here with his family from Jordan in 1993 claiming he'd been tortured and suffered religious persecution. He had been trying to overthrow some despotic Arabic regimes, and because we didn't like them either we granted him asylum in 1994.
In 2001 Abu Qatada was arrested over connections to a German terror cell, but the case was dropped. It was claimed his sermons had been found in the flat used by the 9/11 hijackers, that he'd offered advice to Osama bin Laden, and he gave advice backing suicidal terrorists.
What do you think Britain did with him?
Put him on trial? Use some due process? Ask him if could stop?
No, we ignored lots of warnings from other governments, refused to arrest him, and tried to use him as a spy instead.
Seeing as he was friendly with lots of terrorist types, this brilliant plan quickly failed and in less than a year the British state realised it was being taken for a ride, and brought in a new law saying it could hold terror suspects without trial. Qatada took to his heels, as most of us would.
MI5 looked very silly, the British government looked stupid, and when they finally tracked him down to a council house in in south London they banged him up in Belmarsh. On, as you might expect by this point, no charge whatsoever.
He has spent the years since being shuttled between prisons, fighting a legally aided battle against deportation which has cost at least £3million so far. He's been bailed once or twice to live under surveillance so strict he can't allow a mobile phone to be switched on within his home, in a security operation which costs around £100,000 a week.
He has just been re-arrested for breaching his bail conditions, which are so strict they include banning him from using a motor car, talking to anyone outside the UK, using a computer or mobile phone, or allowing anyone to bring a DVD into his house.
He is barred from having more than one bank account, writing any documents, or attending a mosque.
In short his bail conditions alone infringe his right to freedom to worship, to express himself, and to have free movement. They're astonishingly strict, but then some might say so is he.
Abu Qatada has not been convicted of a single crime in this country. Yet he's been locked up, on an off, for 12 years.
Spies are the only people who say they have evidence of his wrong-doing, but they refuse to present it to an open court, leaving his guilt to be decided not by a jury but by successive Home Secretaries who find him embarrassing.
He's been tried and convicted in his absence in Jordan, but their legal system and human rights record make it equally likely you or I would be convicted of much the same thing if we were citizens and so much as tweeted we didn't like their government. It's not much of a benchmark.
Abu Qatada may well be a man who encourages terror. He might praise bin Laden, condone murder, and find ways to convince the fatally-stupid their prophet wants them to massacre as many people as possible. He might be guilty of all he is accused of.
The problem is that, without evidence or a court hearing, so might you or I. If it crossed Theresa May's mind to crack down on thirtysomething journalists as a security fear I could be banged up in Belmarsh without so much as a by-your-leave.
There is just one thing which separates bad guys from the good guys and it is not that terrorists are all brown, or Muslim, or have hooks and funny physical flaws.
It is that the good guys have decided to treat everyone like they're human, no matter how inhumane their actions.
We have decided that is a given value of 'good', and that it is only by persistently and irritatingly insisting on equal rights for all that we can prove just how fascists, narrow-minded and vicious the alternative is.
We have decided that if you take away human rights what you are left with is human privileges, and that if you start saying who can and can't have them you are on a slippery slope back to the days before we had the Magna Carta.
Men fought and died, defied and bullied their king to get him to sign that document. In the 798 years since the words they forced him to agree have protected millions of Britons and, what's more, have been adopted in the constitutions of free countries all over the world.
Billions of human lives have been, and will be, better because of our equal right to a proper trial. As with all rights they get eroded, and nibbled away at by the authorities, and if we want to keep hold of them we have to each stake a claim and say 'this is ours'.
And that means Abu Qatada too. If he's a hate preacher, let him out to preach his hate, catch him in the act, and then bang him up or deport him. Radical hate preachers rarely turn into pussy cats, in my experience, and if you let him out first off it'll be cheaper and secondly he'll get himself in trouble soon enough.
Deporting him purely for being unlikeable is silly enough. But tearing up one of the few documents which guarantees we cannot be tortured, enslaved, shut up, persecuted, killed or abused is an epic case of cutting off our entire heads to spite our face.
I would rather have my freedoms, and Abu Qatada skipping down the street making an arse of himself, than I would let our government to give up its pretence of being law-abiding.
But then some animals are more equal than others.