Adam Sweeting is relieved to discover that more goes on in the musical world of Jackson Browne than social-political protest - despite Browne's phone being tapped by the police

I had been talking to Jackson Browne about politics, democracy and American foreign policy for 45 minutes, so a change of subject seemed overdue. I wanted to know if the Q Encyclopedia of Rock Stars was correct when it suggested that Browne's 1973 song, Red Neck Friend, was about masturbation.

He looks mildly indignant. "No, no, that's wrong!" he protests. "It's anatomically correct, but not in terms of the particular activity. It's clearly a song about wanting to introduce this girl to my red-neck friend. But Rosie - now that's about masturbation."

Rosie? The one from Running on Empty? "Yeah. Y'know, Rosie Palm and her five sisters? People have listened to that song and loved it for years without knowing that. My mother, who listens to lyrics very thoughtfully, said to me, 'I've finally figured out what that song's about,' and I'm thinking, 'Oh shit'. She said, 'It's about wine, isn't it? Rosé? Am I right?' So I really appreciate that my mother didn't get all the way there imagining that."

It's something of a relief to discover that there is room in Browne-world for topics other than benefit shows for wildlife conservation or protests against war and the death penalty - even if his espousal of environmental and social values did win him the John Steinbeck award, given to "artists and humanitarians whose works exemplify values found in Steinbeck's writings" - last year.

His latest album, The Naked Ride Home, draws attention to the way the rich are insulated from the poor, and one song, Casino Nation, laments the way the American public's obsession with instant TV fame blinds them to manipulation by an authoritarian state. Most of the songs, however, are to do with personal relationships or inner states of mind, and Browne opens the album with the attention-grabbing title track, which describes a woman taking her clothes off in the front seat of his car.

"I admit it's a little bit of a trick, to engage people's prurient interest and then turn the story a different way, but actually that's the way the story unfolded," he says. "That song is about the end of a marriage, but it's also about the difference between the two people. It's a moment of awakening when the guy in the song realises that neither of them is thinking of each other or the relationship in the same way. And The Naked Ride Home makes a good title for the album, too - the whole idea of needing to be naked to encounter the truth."

It seems a reasonable bet that the album reflects the break-up of his second marriage, to Australian model Lynne Sweeney, whose reaction to being turned into songwriting fodder is not on record. They divorced during the 1980s, when Browne was in the middle of a lengthy affair with actress Daryl Hannah. That relationship recently came back to haunt Jackson when the Atlanta-based cable channel TBS Superstation broadcast America's Prince: The John F Kennedy Jr Story, in which Kennedy was depicted as rescuing Hannah after Browne allegedly beat her up. "Mr Browne has never assaulted Daryl Hannah," said his American publicist, and the singer is insisting that the film not be rebroadcast until what he claims are defamatory scenes have been removed.

A mild whiff of notoriety may be no bad thing for Browne, if only as an antidote to his long-standing reputation for extreme earnestness. Paradoxically, he has always looked impossibly young while seeming artistically older than his years, writing infinitely weary songs about death, disillusion and apocalypse when still in his early 20s. Now, at 54, he still has the impeccable hair and actorly bone structure that have graced his album covers since his début in 1972, but he seems to have found a better balance between the art and the artist. One of the gratifying qualities of The Naked Ride Home - apart from the fact that it is his best batch of songs in a decade - is the way Browne has turned away from the "important message" phase that made discs like Lives in the Balance or World in Motion so effective at emptying the room at parties.

Browne first went public in his new role as rock'n'roll polemicist at the anti-nuclear Musicians United for Safe Energy (Muse) concerts in New York in 1979, where he was joined by Bruce Springsteen, Bonnie Raitt, Carly Simon and other concerned luminaries. To anybody who had assumed that Browne was just another self-absorbed balladeer from lotus-land, this new, direct-action Jackson came as something of a shock.

My observation bemuses him. "I don't think of California in that way, and I don't think of myself in that way," he frowns.

"It's always a surprise when anybody says anything politically, don't you think? Were you surprised that Marvin Gaye suddenly wrote this song What's Going On, and that the most articulate and deeply felt anti-war song of the time was written by somebody that was not considered political at all?"

There is no doubting the depth of Browne's convictions, or the thoroughness with which he has researched the issues that matter to him. Only the fact that he has a plane to catch prevents him from holding forth all afternoon about his favourite topics, such as the way George W. Bush became president despite polling fewer votes than Al Gore ("Does that mean Gore had to win by more than a majority to be the president?"), or the way the FBI failed to detect al-Qaida's plans because it was too busy quashing American political dissidents. The discovery that his phone had been tapped by the Los Angeles police department confirmed that he was right to be paranoid.

"I was a party to a lawsuit by the American Civil Liberties Union, where it became evident that the LAPD was spying on a number of people in the peace movement or the solidarity with central America movement. They'd been illegally wiretapping and acquiring information, and passing it to a right-wing computer bank called the Western Goals computer databank, or something. The LAPD, which is notoriously corrupt, portrayed this as being done by a rogue element, but who knows really?"

Despite Browne's hectic schedule of good causes, he has never lost sight of the fact that it is his music that has given him a platform for him to voice his opinions. He has also been a consistent champion of musical friends and colleagues, helping Warren Zevon to sign a deal with Asylum and producing his first two albums, and more recently rallying round the ailing David Crosby during his liver transplant ordeal.

Zevon's diagnosis of lung cancer hit Browne hard. "It's heartbreaking news," he says, "because he's a really good friend and a huge contributor to our music. He has this really darkly funny view of the world and of mortality. It's prophetic and ironic that he wrote this song Life'll Kill Ya only recently, but I just wish it weren't true. I wish I could pick up the paper and find that it was a mistaken diagnosis."

When I met Zevon a couple of years ago, he repaid the compliment, in a sense. He wasn't buying my theory that Jackson was the classic Mr LA, very laid-back with lots of harmonies. "I have harmonies," Zevon protested. "I think of the songs he's written about deceased friends of ours, and they're much less easily dismissed than my own songs about death. No, Jackson's more complex and . . . I dunno . . . dark." And, as Zevon also pointed out, Jackson still has perfect hair.

Jackson Browne plays Millennium Forum, Derry tonight and Olympia Dublin tomorrow