EMMA ALBERICI, PRESENTER: The pork industry has dramatically raised the stakes in an increasingly rancorous battle against animal welfare campaigners. Pig farmers are using a suite of unprecedented legal tactics in retaliation against groups who secretly film piggeries and post the images on the internet. And as John Stewart reports, as some politicians here and in the US are backing moves to crackdown on activists who go public with footage without first showing it to authorities. And a warning, some viewers may find the images in this story disturbing.

JOHN STEWART, REPORTER: The pork industry and animal rights activists are locked in battle over the reputation and image of pig farming in Australia.

PORK INDUSTRY VIDEO: Hi, I'm Donna and welcome to my maternity ward. I turn up from Monday to Saturday looking after these little fellas.

JOHN STEWART: Earlier this year activist secretly filmed this piggery in the NSW town of Young, then posted it on YouTube.

The farmer, Ean Pollard, made his own video.

PORK INDUSTRY VIDEO: Hi, I'm Ean. I'm an Australian pork producer and I raise good quality pork for Australians to put on their plate.

JOHN STEWART: He used the same animal liberation in his counterattack.

PORK INDUSTRY VIDEO: You may have seen some footage that activists have taken, of sows that have been woken up early in the morning and expected to be fed and then when they weren't fed they got upset.

JOHN STEWART: Another farm also in Young was secretly filmed by animal rights activists who left hidden cameras inside the pig sheds.

The farm is owned by Edwina Beveridge.

EDWINA BEVERIDGE, PIG FARMER: Oh, I feel absolutely terrified, violated. I have a young family, I live on our farm, our farm's quite close to the pig farm, an awful feeling.

JOHN STEWART: Edwina Beveridge and Ean Pollard have placed interim apprehended violence orders against the executive director of Animal Liberation Mark Pearson to try and stop animal rights groups trespassing on their properties.

EDWINA BEVERIDGE: I'm genuinely frightened for my safety and my family's safety so I've taken out an AVO because I would really like to know that he can't come near me.

JOHN STEWART: Mark Pearson says he had never met or spoken with either of the farmers and denies that he was on their farms. But he insists the intensive farming practices of the pork industry should be exposed.

MARK PEARSON, EXECUTIVE DIRECTOR, ANIMAL LIBERATION: The documentation is now being gathered from a lot of these places which are just hidden sheds, out of sight, out of mind, that's the way the industry wants it to continue and now the door's been flung open, the spotlight's been put on their practices and they're having to answer to it.

JOHN STEWART: AVOs are not the only legal measure being used by the pork industry. Last year the owners of the Windridge Piggery at Young tried to obtain copyright of this footage filmed by Animal Liberation but the Supreme Court ruled against the pork industry. In another legal move two months ago the Australian pork industry lodged a formal complaint about the domain name Aussie pigs.com.au, a website set up by Animal Liberation.

ANDREW SPENCER, CEO, AUSTRALIAN PORK LIMITED: The website Aussiepigs.com.au is basically a sight where our pig farmers are being defamed. It doesn't represent Aussie pigs, it represents a vegetarian website where they're against animal farming, and we think that that's completely crazy.

JOHN STEWART: But last week the pork industry also lost that case and Animal Liberation retain ed ownership of the domain name. Some politicians want Australia to follow the lead of some American States, like Kansas, Montana and North Dakota which have made it illegal for activists to film farm animals. Activists can also be forced to hand over images of animal cruelty to authorities within 48 hours of being filmed.

In Australia, Liberal Senator Chris Back is leading the local push.

CHRIS BACK, LIBERAL SENATOR: Anybody who comes into the possession of information, and in this case which may be leading towards animal cruelty, anybody in my view should have to present that material as quickly as possible to relevant authorities and indeed the question should be asked: if they're unwilling to do so and don't want to do so and withhold that information for days or weeks or months, then I would be expecting the media and the wider community to actually be asking them why they've withheld that information.

JOHN STEWART: Mark Pearson says that's an attempt to censor the material and stop the images being published on the Internet.

MARK PEARSON: My view it will very quickly fall over and it will be another tactic that the pig industry is trying through a court system that is doomed to fail. But we're not surprised, in a sense, because all these are measures of an industry that is desperate and being brought to its knees and that being brought to its knees is their own doing because they're not waking up and seeing what's going on and moving in the right direction to help out these animals.

JOHN STEWART: The Australian pork industry has agreed to fazing out the use of sow stalls by 2017 and says that if animal rights groups damage the local industry, pork will be imported from countries with far lower animal welfare standards.

ANDREW SPENCER: If these organisations really cared about pig welfare they would be standing side by side with the industry, especially considering that nearly half of all the pork that we consume here in Australia is coming from overseas, it's coming from countries that still use sow stalls and they have no intention of stopping using sow stalls.

JOHN STEWART: According to Mark Pearson, the supermarket giants Coles and Woolworths are putting pressure on the pork industry to raise animal welfare standards. But he says that farmers are moving too slow.

MARK PEARSON: Well they're certainly digging their heels in and resisting but it will be to their own detriment because their products will end up staying in their refrigerators and shelves on the piggery or at the abattoir. And the retails, who have enormous power in these situations, just won't buy it.

JOHN STEWART: The legal battle between the pork industry and animal rights activists isn't over yet. But for now the Internet and YouTube are providing animal welfare groups with a powerful weapon.

John Stewart Lateline.