Technically Sean Penn might be middle aged. But the 44-year-old seems to be as much of a rebel as ever.

He picked up an Oscar for his role in Mystic River last year – but took the opportunity to sneak in a comment about his opposition to the war in Iraq.

In fact the actor has had a string of Oscar, Bafta and Golden Globe nominations thanks to controversial and hard-hitting roles in films like 21 Grams, I Am Sam and Dead Man Walking – but has made as many headlines for his hot temper, his dislike of the paparazzi and his outspoken political views.

With as many staunch supporters as detractors, the actor simply doesn’t care.

“I’ve never been able to feel particularly likeable or inclined to pursue it. It’s like director Louis Malle said about women, ‘They either like you or they don’t’.” One thing he certainly is, is respected – in particular for his obvious acting talent.

And he’s followed up a strong of emotionally and politically charged roles with two new hard- hitting films – The Assassination Of Richard Nixon, opening on this Friday (April 8), and The Interpreter, opening on Friday April 15.

The former, based on a true story, sees Sean as a struggling salesman who decides on revenge when the American Dream eludes him.

As his life disintegrates around him – his wife, played by Naomi Watts, leaves him, and the business loan he hopes will transform his life is turned down – he descends into madness and alienation, culminating in his plan to assassinate Nixon by flying a plane into the White House.

It was a tough character to play but he felt drawn to doing it, he says.

“I think it was the hardest one to make, it was misery, but I’m very proud of the result.” In Sydney Pollack’s more mainstream The Interpreter, Sean portrays a federal agent who has to protect a UN interpreter, played by Nicole Kidman, who may be the target of assassination.

The film marks the first time that the UN has allowed a movie crew to shoot inside the New York headquarters of the world body – even Alfred Hitchcock was turned down for North By Northwest.

Both these films show Sean at his best – the brooding intensity, a willingness to show ordinary men battling extraordinary situations and a distinctly unfashionable political consciousness.

But although the star took out newspaper advertisements explaining his opposition to President Bush’s invasion of Iraq two years ago, he doesn’t like to think of himself as a political activist.

“Political activist is somebody else’s term, not mine. I think I am a moderately responsible citizen,” he maintains.

“If I was more than that, I would have done a lot more.” But he does believe that an actor should reflect the times in which he lives.

“Something of the present culture has to be siphoned through the work.” And he adds: “I don’t think there’s enough political films here or anywhere.” While he isn’t opposed to more light-hearted films, his choices tend towards movies he feels he has an emotional stake in.

“I can enjoy the Hollywood blockbuster like anyone else, but I would feel unfulfilled if I didn’t try to make something that has some substance to it,” he says.

“There’s room for supermarket novels and there’s room for a literature section. I hope it’s the same in film. I think the biggest thing is to not participate in the damaging, lying cinema.” He also knows his choices have put him outside the star-making mainstream – although that’s not something he’s ever craved.

“I can never get ahead of the game because of the movies I do,” he admits.

“Courage in cinema is looking someone in the eye and telling him the truth, you owe the audience that. It’s about choice, you have the freedom to not be free.” What makes the actor all the more remarkable for his decisions is that he grew up in the heart of Tinseltown itself – the son of actress Eileen Ryan, who incidentally also appears in The Assassination Of Richard Nixon, and late director Leo Penn.

As an angry young man, he made as many headlines for his hot temper and his high-voltage marriage to Madonna, which resulted in critically-panned film Shanghai Surprise, and a constant media circus.

20 years on from his first wedding, Sean is now a father of two – Dylan Frances, 13, and 11-year-old Hopper Jack – with actress wife Robin Wright Penn.

A combination of growing older and fatherhood have calmed him down, he admits.

“The clothes of your life start to fit in middle age. The stakes are raised the more life you’ve lived, the more significant places you can take a character. You understand more, you have a deeper perspective.

He adds: “I wouldn’t say that I’m a changed man in that I’m wildly happy as a person and the world looks beautiful to me every day. But I’m enjoying my life with Robin and our kids more than I ever have and I think I appreciate my family in ways that I was probably too stupid to have done before.” In some ways though, he doesn’t think his beliefs and convictions are too different than most people.

“I believe the level of rage that I have is shared, that everyone has it in some way. Acting is a great outlet if you accept that it’s there.” Wife Robin, who has called living with him “beautiful torture” agrees. “I don’t know whether it comes with age or you just get too tired of it. You know he’s just so tired of fighting.” The family live out of the media spotlight of southern California, based in Marin County, north of San Francisco.

“I got tired of a lot of aspects of Los Angeles, the main one being raising the kids in a company town,” explains Sean.

But he’s not turning his back on politics just yet – the actor is currently filming All The King’s Men, in which he plays an opportunist Southern politician, modelled on the controversial Governor Huey Long of Louisiana.

“It’s a funny thing about politics and movies, all we do with movies is take an idea and fuel it.

“All you can do is hope.”