Jude Law was nominated for an acclaimed perfromance in Hamlet, but lost to Mark Rylance who played charismatic rebel in Jez Butterworth's Jerusalem. Image Credit: AP

Jude Law can't speak about phone hacking, I am told by his publicist before the interview. And when I bring it up during our chat — it is the day after the Murdochs and Rebekah Brooks have given testimonies to the Commons committee — Law smiles and makes a zipping action with his finger across his lips. "I just can't because I'm in legal proceedings and it's in various stages with various people, and part of that is classified, and they've promised to keep it quiet if I keep it quiet. But believe me, there's an awful lot I want to say, though. An awful lot."

But then he can't not speak about it either. The phone-hacking years coincided with the Jude Law-tabloid-mania years and he has not one case pending against News International but three. His relationship with the tabloid press, particularly News International, has defined and circumscribed his life for much of the past decade.

We are in an empty meeting room at the Jerwood Space in south London, where Law is in the thick of rehearsals for his new play, an Eugene O'Neill revival, Anna Christie. It will show at the Donmar Warehouse until October and his head is full of it: It is a gritty love story set in 1920 between a prostitute and a ship's stoker.

He is right in the middle of one drama — he plays the ship's stoker, Mat Burke — but, of course, he can't help but be compelled by the other spectacle playing itself out on the television news. "I mean, of course I'm watching it," he says. "Who isn't?"

And you have already got your role sorted, I say, meaning that, of course, if it ever was a film, he could simply play himself. But he doesn't catch my drift.

"James, you mean?" And then realises his mistake. "Oh! You mean myself? Oh dear. I can't believe I said that." But, of course, he would be brilliant as James Murdoch. He has specialised in characters who have an edge, a slightly slippery elusiveness, and there are obvious overtones of what is still, perhaps, his most famous role — the role that saw him burst into public consciousness in Anthony Minghella's The Talented Mr Ripley in 1999: the heir to a shipping fortune, Dickie Greenleaf. There really is more than a touch of Dickie Greenleaf to James Murdoch, isn't there, I say.

"Oh dear," he says. "I've got to be really careful what I say here."

He is obviously itching to speak about it. Phone hacking, privacy, press intrusion — these are matters that he has thought long and hard about but because he can't go into details, he ends up delivering slightly gnomic one-liners. "The thing is," he says, "it involves us all. We're all complicit."

Do you think it is just the beginning, I say. "I hope it's just the beginning." And he makes the zipping action across his lips again. "I don't want to quote myself, so I'm going to quote someone else. There was an interesting Thought for the Day on Radio 4 yesterday. I came in halfway through, so I don't know who it was, but he was talking about Murdoch being sorry. No, he was saying that he was asking for atonement. And the guy said, he hasn't been judged yet. He hasn't any right to ask for that yet because we still have to judge him. And judgment is what this whole thing is about. They judge people. Those papers have judged people. I have been judged. They have yet to all be judged and I hope they are ready for it."

He is referring, of course, to the time when, for a while, he was one half of the most glamorous couple on Earth, the Jude Law-Sienna Miller coupling, a gift to tabloid editors and celebrity magazines everywhere. He was the Oscar-nominated, chisel-jawed actor, and Miller was his golden-haired consort. They seemed to embody beauty and talent, right up until the News of the World printed a story which detailed how Law had had an affair with his children's nanny and all tabloid hell broke loose. Miller left. Law made a public apology. Soap opera ensued. And then just as that was dying down, in 2009, another story in the News of the World detailed he had had a fling with an American model, Samantha Burke, who was subsequently carrying his child.

They are not incidents Law is proud of but they are also not incidents which have anything to do with his day job — acting — and what the phone-hacking case seems to have done, I say, is to throw open the whole concept of privacy. Of who is entitled to a private life and what that means. "Well, again I use this word judgment. It's someone thinking that they have the right to have a moral judgment when a) there is no recourse. I'm not going to be able to morally judge them back and say, ‘Well, let me look at your life.' And b) is that healthy?."

No place for nostalgia

The new play, Anna Christie, is part of the final season of the Donmar's artistic director, Michael Grandage, who in 2009 directed Law in Hamlet, a role that saw him feted by the critics and nominated for an Olivier award. He started out in the theatre and was a successful stage actor long before he was a film star: He was nominated for his first Olivier (best newcomer) for his first West End play, Les Parents Terribles.

I wonder if he is nostalgic for that period — when he had success without this all-encompassing fame. "I don't really look back. I've always been someone who's really tried to live in the here and now. My memory isn't very good, so maybe that's why, but it just seems like I've been living this life, my present chapter, for a long time and I don't remember what it was like before."

His thirties (he is 38 now) have been, at best, a mixed time. As a young man, he was a self-described idealist. "I was an optimist, a great champion of the human spirit. And I lost that for a time. I feel like I've regained a bit of that in the past few years but there was a period of my life in which I had a very low opinion of people in general."

What, I say? The entire human race?

"Well, yeah. I just felt a bit down on what people seemed to be interested in. And what the general consensus of what the interesting things were. It was just so far away from what I found interesting and what I found fascinating about people. It just felt like this slurry pit."

And at the heart of the slurry pit was the tabloid press. The three cases he is bringing against News International are some of the most crucial, and possibly damaging, of them all. The first accuses the News of the World of tapping his and his assistant's phone in New York in 2003: the first case to be brought that is alleged to have happened on United States soil, potentially jeopardising Murdoch's entire American news operation. Another is against the Sun for hacking into his phone in 2005 and 2006 — when Rebekah Brooks was editor. And the third is against the News of the World which has been selected to be a test case in a civil litigation action brought by 30 public figures. His case was selected to determine how far up the chain of command the decision went: Law's QC alleges it was a "very senior News of the World executive" who authorised Law's phone to be hacked.

But it goes even deeper than that. When looking through old cuttings, I find an interview that Law did with the Observer in 2003 before any of this came to light, in which he talked about two instances in which he called the police to the house he was then sharing with his wife, Sadie Frost, and their children, and which subsequently ended up in the newspapers. And another instance in which his decree nisi was sent directly from the high court to a British tabloid "before it was sent to me". It was, he claimed, "the high court and then the police selling stories, so how are you going to live in the country and feel safe?"

You really felt like the establishment wasn't working? That it was corrupt?

"Yes. Truly. That's certainly how I felt. But having said that, I've also been treated really well by the police, where they've been really helpful, so it's clearly individuals."

But it is a fundamental pillar of democracy to have a police force you can trust.

"Yes, it does come down to fundamentals. I still believe in the democracy of our parliament. Even though none of it has clearly been working. I also, for the first time for a long time, wouldn't want to live anywhere else. I went through a long period of feeling really uncomfortable in this country, just feeling really harassed and chased. And I couldn't move because my children are growing up here and their mum lives here, and we've got a really good set-up where we have a very healthy 50-50 custody arrangement. But I came back in 2009 from New York — I'd been living there for three months with the children — and I completely fell in love with London again."

What he has done, he says, is to "work out a way around the system". There has been a process of finding a way of being in the city with his children — Rafferty, 14, Iris, 10, and Rudy, 8 (he is also supporting Sophia, 22 months, his daughter born to Samantha Burke in the US). "I've created a haven that works for me and my family that hasn't necessarily involved the law. I still enjoy a very normal life with my children. We use trains and buses and that's often the best way. If you build up some sort of psychological bubble around you, I think you're asking for trouble."

In some ways, it sounds as if Law has got his midlife crisis out of the way early. "I really feel the years between 40 and 50 are going to be the most productive in my life. It's just a great age to be an actor. It's a bit of a minefield being 20 because you've got all these aspirations and ideals. And then you get cynical. And for me, my thirties have been about re-evaluating what I'm doing. And now I want to get back into production and I've always been interested in directing, and my children are all at an age where I don't have to be tied to London."

Struggling against a stereotype

As a younger man, Law struggled against being defined by his looks. At 38, even heavily muffled by the beard he has been growing for Anna Christie, he is still an undeniably handsome man. But there is a wider range of roles available to him now: He had the looks of a romantic lead, but always hankered after the character roles. "I felt a bit disappointed that that's what people wanted me to be, whereas I felt that I had lots of things to offer."

Growing older has possibly come as something of a relief. His new films due out later this year include Anna Karenina, with a new script by Tom Stoppard, in which he plays not dashing Vronsky, but cuckolded Karenin opposite Keira Knightley.

In Law's case, getting older has been accompanied by a rather enforced getting of wisdom. It has been a long, hard, public process. He has also grown wary not just of the press but of talking about anything — his life, his work. "I want to be seen doing my work and I'm tired of being talked about for what I'm wearing or who I've been seen with. I don't even want to talk about my acting, because I think it should talk for itself." He even doesn't really want to talk about the causes he supports.

Law just doesn't seem to play the A-list celebrity, but then he "hates the word celebrity which means that I am in some sort of messy, mushy bracket with people who have won reality shows and chefs and socialites. I've never courted the press unless I'm talking to them about some work I'm doing. And I don't do that very much. There's just been so much cynicism. Why are you banging your drum about this? Or why are you going on about that?"

His other big cause is Peace One Day, an organisation which is attempting to make September 21 recognised as a day of peace throughout the world. It is an ambitious idea, dreamt up by an Englishman called Jeremy Gilley. Law agreed to make a video appeal for Gilley in 2007 and ended up travelling out to Afghanistan with him to try and make the ceasefire actually happen.

If Afghanistan seems to have been one turning point in his life, the phone-hacking cases will certainly be another. "People in the public eye are seen as cosseted and spoilt. This idea of what have you to complain about? But it's basic demands of privacy. Because it's your life being invaded, used to not report, but make stories."

So, does it constitute a revolution, as some have suggested? "We'll have to wait and see, won't we? You never know when you're in the middle of something. You can only tell later." And the same probably applies to him too. He could be right — his forties may well be his best years yet.