Image caption Gibson fans have a lifelong affection for the sound, but little idea about where their guitars come from

Iconic US guitar maker Gibson is facing a criminal probe over claims it broke environmental laws while importing wood. So is music the next threat to the world's forests?

"Up here you grow up liking Fenders or you grow up liking Gibsons," says Billy Jack, 55, sat in a Nashville music store eyeing up a trio of shiny new Gibson guitars.

Cradling a $3,800 (£2,413) Gibson Les Paul, Mr Jack, a veteran guitarist, recalls riffs gone by as he explains his fondness for one of rock's iconic instruments.

"You can hear it in your ear. It's how quickly you can run through your chops. It's the tone. You just can't go wrong."

But things have gone wrong. On 28 August federal agents raided Gibson's Nashville and Memphis premises, seizing shipments of Indian rosewood and leaving the venerable guitar maker more than a little off-key.

The agents brandished search warrants issued amid suspicions that Gibson had violated the terms of the Lacey Act, an environmental law that requires imports to the US to comply with laws in the country of origin as well.

Gibson: An American icon Founded by Orville Gibson in the 1890s

Primarily made acoustic guitars until 1950s

Les Paul electric became hugely popular

Famous Gibson guitarists include Elvis, Eric Clapton, Jimmy Page, The Edge

Bought out in 1986 by Henry Juszkiewicz and David Berryman

It was the second raid on Gibson since the Lacey Act was amended in 2008.

Gibson is now a conservative cause celebre, with anti-Washington activists in Tennessee and beyond hailing the firm's predicament as an example of the "unacceptable over-reach" of the US federal government.

Facing a criminal investigation, Gibson boss Henry Juszkiewicz has formed an uneasy alliance with the Tea Party, even appearing on stage in Nashville at a sun-drenched weekend rally called to support his firm.

Introduced to a cheering 500-strong crowd as "the man who stood up to the federal government", the mild-mannered Mr Juszkiewicz followed a string of tub-thumping speeches and political country music acts.

But he seemed hesitant to add his voice to the anti-Washington, anti-regulation clamour, instead urging the crowd to keep fighting "injustice and unfairness".

Offstage Mr Juszkiewicz - who denies any wrongdoing - had a decidedly un-Tea Party take on things: "I'm a very strong believer in socially responsible sourcing and I think the government needs to be involved to ensure that happens," he says.

"But there's a difference between intervention and over-reach."

Tariff dispute

Mr Juszkiewicz values the seized wood at $500,000 (£317,517). That's enough rosewood for 10,000 fingerboards - a strip running along the neck of the guitar vital to the overall tone and performance of the instrument.

Woods used in a Gibson Les Paul guitar Source: Greenpeace USA

With Gibson's production lines badly hit, the firm is seeking alternative supplies. But finding new wood will not be easy.

Illegal logging means reputable supplies of wood used to make guitars are scarcer, and more heavily regulated, than ever before.

Brazilian rosewood - dalbergia nigra - regarded by some guitarists as the "holy grail", is effectively unavailable, officially listed as an endangered species. The export of ebony and rosewood from Madagascar has been banned amid pressure from environmental groups. They are available from India, but only under certain conditions.

Yet the demand for an ever-dwindling supply of hardwoods is not letting up: Gibson alone produces some 700 guitars a day, according to Mr Juszkiewicz.

Two years after a shipment of Madagascan ebony was confiscated, Gibson ran into trouble when a shipment from India arrived in Dallas this June. According to a federal affidavit, the wood was brought into the US under a tariff code that made it illegal to export from India - thus violating the Lacey Act.

Henry Juszkiewicz insists the wood is from a sustainable source, and the dispute is really over tariff coding. Gibson has letters from the Indian government supporting its interpretation, Mr Juszkiewicz says, but they have not been made public.

"The government is using innuendo with words like 'fraudulently', as if there was some deception taking place. We've been purchasing that wood for 17 years exactly the same way."

In any case, he insists, an armed raid "should not be the first response to an import-export issue".

Media playback is unsupported on your device Media caption Gibson's Henry Juszkiewicz on his alliance with the Tea Party

Dubious sourcing

It is the armed raid that has now polarised the debate around Gibson and given it a wider political resonance.

For the Tea Party, and for local Republican Congresswoman Marsha Blackburn, the sight of federal agents raiding an iconic American company symbolises everything wrong with modern-day Washington.

"What I've heard from people is: 'If it can happen to Gibson it can happen to me,'" Ms Blackburn tells the Nashville rally.

"Why Gibson?" she asks offstage, alluding to a widely-held belief among conservatives that Gibson had been unfairly singled out. "There are concerns about selective enforcement. That's something that we can help with in Congress."

Even supporters of the Lacey Act admit compliance is a tricky and subjective business.

The two Gibson cases are the first cases under Lacey since forest products were added to the legislation in 2008, according to Scott Paul, director of forest campaigns for Greenpeace USA.

Image caption The Gibson boss (c) was a guest of House Speaker John Boehner at Congress in September

Despite the criminal probe, there is "no suggestion that the Indian wood was cut illegally," he says. Instead the debate rests - as Henry Juszkiewicz contends - on the tariff coding.

Natalie Swango, manager of Luthiers Mercantile, the California-based import firm that brought the Gibson wood into the US, says there are clear dangers of criminalising the import of legally sourced wood.

"We are importing from a country [India] that grows its trees in state-owned forests," she says. "My concern is that without amendments to the Lacey Act we may be forced to go to a country like Mexico, or Indonesia, where they are not watching their forests so closely."

The 2009 Gibson raid, though, could have more serious repercussions. In that case the firm is suspected of knowingly importing wood from Madagascar that was cut illegally.

"Everyone is innocent until proven guilty," Greenpeace's Scott Paul says of that case, while warning that the industry as a whole has questions to answer.

"There has always been an underlying feeling that a significant proportion of the wood used in musical instruments has come from illegal or highly dubious sources."

Preserving the sound

Instead of threatening the future of America's guitars, though, one veteran musician hopes the furore can prod the industry towards a sustainable future.

"The wood that goes into guitars is crucial to the tone of the instrument," says Laurence Juber, an acoustic guitarist who lined up with Sir Paul McCartney in Wings.

"I can show you the difference in sound between Indian rosewood and Brazilian rosewood and ebony and maple."

Failing to protect global forests could lead to changes in the ways guitars are designed and constructed, Mr Juber adds. That's not something guaranteed to preserve the musical experience as we know it, and it's something he wants to prevent.

"Hopefully I can help keep the industry alive and in 300 years people will also be able to play guitars and get some pleasure out of them."

In Nashville, Billy Jack was not thinking about the trees felled to craft his new Les Paul. He had faith his favourite guitar maker would come good in the end.

"If Gibson have an environmental issue then they will have to change their wood. And I'm sure they will do the right thing because they have been in the industry so long.

"In the end, it's their reputation on the line."