Opera, says almost everyone, needs to become more relevant. But what happens when someone writes one that is? In 1991, the world premiere took place of an opera by the pre-eminent American composer John Adams that could scarcely be more "relevant". It relates the true story of the 1985 hijacking by Palestinian terrorists of the Achille Lauro cruise ship, and the murder of a wheelchair-bound Jewish-American passenger, Leon Klinghoffer. So controversial was this work, The Death of Klinghoffer, that no London opera house has ever dared to stage it before.
Now, finally, English National Opera is about to change that. Its production, opening this month and directed by Tom Morris, co-director of the stage production of War Horse, promises to be a landmark occasion.
The backlash over Klinghoffer in the past two decades has frequently proved vicious. This is a work that dares to give a voice to terrorists as well as the terrorised; to some, this remains anathema. It is not least the opera's many-hued acknowledgement of unpalatable subtleties in the human condition that has caused the trouble – after all, the world often prefers to see such matters in black and white. For instance, Adams presents a chorus of exiled Jews; he also includes a chorus of exiled Palestinians; and the terrorists themselves are as rounded in character as their victims.
Back in 1991, two of its five co-commissioning houses – Glyndebourne and Los Angeles Opera – chickened out of staging Klinghoffer altogether. Protests by the Jewish Information League greeted it at the San Francisco Opera a year later. A Boston concert featuring parts of it was cancelled two months after 9/11. And in an extraordinary attack, also in the aftermath of 9/11, the musicologist Richard Taruskin in The New York Times accused the opera of "romanticizing terrorism" and being "anti-American, anti-Semitic and anti-bourgeois", effectively calling for it not to be performed again. John Adams remarked in response that this was like "being bombed from 30,000ft by a B-52".
It is, without doubt, the fear of provoking such adverse response, upsetting those who have been affected by terrorism and possibly risking the wrath of audience members or supporters that has kept Klinghoffer out for so long. This is a crying shame. As is usual in such cases, many of those protesting about the opera had not even seen it, but the result was that others were denied the chance to assess it on the reality of its own merits.
But the opera has refused to go away; it is too important for that. Slowly, it has sneaked back into view. Penny Woolcock directed a film of it for Channel 4 in 2003; the Barbican hosted a concert performance in 2002 and Scottish Opera staged it at the Edinburgh Festival in 2005. Even the US is starting to listen. Last year, the Opera Theatre of St Louis presented it, to relative calm, and Morris's production for ENO is also planned for the Met in New York.
London is not generally backward in coming forward where controversial art is concerned, but the climate here surrounding discussions of the Israeli-Palestinian situation is if anything more vituperative than ever. ENO is therefore taking a major risk.
Klinghoffer's librettist, Alice Goodman, declares: "I think that ENO is being tremendously exciting and brave, sticking its neck above the parapet to put it on." And in her view, the opera might now do some good. "In some respects, the production in St Louis used the controversy connected with the opera to bring people together to have actual conversations about the questions it raised, rather than using it as an opportunity to heave bricks."
That issue is a major problem with discussions about the Middle East. Each side remains so convinced of its own rectitude that persuading anybody to listen to an alternative viewpoint has become virtually impossible. An opera, though, requires its audience to be quiet and absorb it. In Klinghoffer's case, this means taking in a variety of different, essentially human angles for a good two and a half hours.
Can this make a difference? "I don't think the opera will have any effect, alas, upon the situation in the Middle East," says Goodman. "I think where it can be helpful is in the life of this country and this city, which is so wonderfully diverse both in its religions and in its political opinions. It can be a centre for imagining the interior lives, the experience and the feelings of 'the other'."
Goodman adds that in her libretto she intended "to tell the truth as clearly as I could about the situation. I don't think I was setting out to be even-handed. The people who kill are killers. But I was trying to recognise this absolute truth: that the person who wants to kill you, the person who hates you, the person who doesn't understand you, is likewise a human being. The old man in a wheelchair who dislikes you is a human being. And that humanity isn't really even-handedness; it is simply looking at things in more than two dimensions.
"Shakespeare does this constantly. In Coriolanus, for instance, every character is unsympathetic, but you identify with the voice of the play, which speaks for them all. In Klinghoffer the equivalent might be the choruses. But people who kill and hijack do get to sing beautiful songs, and people who are heroic – the Klinghoffers and the Captain – are not necessarily attractive. People are capable of that degree of moral complexity." In the 20 years since the work's premiere, Goodman has been ordained; she is now a vicar in Cambridgeshire.
The conductor Baldur Brönnimann, who takes the musical helm for this production, has worked in both Israel and the West Bank and sees his own impressions reflected in the opera's approach. "It doesn't pass judgment too easily," he says, "but concerns individual characters, rather than any political perspective. It looks at the trees rather than the forest.
"When I was in Bethlehem, where the rehearsal space was next to the Church of the Nativity, people would come up to me and say, 'We have a story to tell – it's important that people know what's going on here.' What you receive is not a big political picture, but a collage of impressions from individuals dealing with their daily problems: this is the reality of life. Adams's opera is close to that reality." The music itself, he adds, does not take a stand: "It is often very reflective – it puts things on to a higher plane.
"Opera, which too often can be seen as a safe house from reality, shouldn't avoid going to places like this," he adds. "It's important that these questions are not left only to extremists. There has to be a discussion that is more humane, sensible and personal. This piece gives everybody a voice; that is what's needed. I'm happy we can do a piece that's as relevant as that."
John Berry, artistic director of ENO, is not anxious about the furores around the piece, though says he is "mindful" of them. "We've talked about security, but at this stage there's no indication that it will be a problem," he says. "And the political content doesn't worry me, because this is what music and theatre are all about. Some people say music and politics should be completely separate, but I don't agree. They are absolutely part of the same world." He adds wryly that opera audiences are passionately opinionated about pretty much everything: "I've had three death threats – but they were all because of Don Giovanni."
Besides, the company's ongoing association with John Adams could bring some exciting consequences long-term. This is their third major Adams staging, following recent successes with Nixon in China and Doctor Atomic. Berry declares: "I hope that John Adams will write his next opera for ENO."
And now, says Brönnimann, we should sit down and listen. "After all that has been said about Klinghoffer and all the stories it has created, it's time to let the music speak for itself."
'The Death of Klinghoffer', London Coliseum, WC2 (0871 911 0200) 25 February to 9 March