The Animal Liberation Front (ALF) is an international, underground leaderless resistance that engages in illegal direct action on behalf of animals. Activists see themselves as a modern-day Underground Railroad, the 19th-century anti-slavery network, removing animals from laboratories and farms, destroying facilities, arranging safe houses and veterinary care, and operating sanctuaries where the animals live out the rest of their lives. According to the ALF's code, any act that furthers the cause of animal liberation, where all reasonable precautions are taken not to harm human or non-human life, may be claimed as an ALF action.

Activists say the movement is non-violent. In Behind the Mask, a 2006 documentary, American activist Rod Coronado said: "One thing that I know that separates us from the people we are constantly accused of being—that is, terrorists, violent criminals—is the fact that we have harmed no one." There has nevertheless been widespread criticism that ALF spokespersons and activists have either failed to condemn acts of violence or have themselves engaged in it. The Southern Poverty Law Center (SPLC), which monitors U.S. domestic extremism, has noted the involvement of ALF activists in the Stop Huntingdon Animal Cruelty campaign, which SPLC identifies as using "frankly terroristic tactics", and in January 2005, the ALF was listed in a draft planning document as a domestic terrorist threat by the United States Department of Homeland Security

In December 1963, John Prestige, a journalist from Brixham, Devon, was assigned to cover a Devon and Somerset Staghounds event, where he watched hunters chase and kill a pregnant deer. In protest, he formed the Hunt Saboteurs Association (HSA)—with the support of the League Against Cruel Sports, according to The Guardian—which evolved into groups of volunteers trained to thwart the hunts' hounds by blowing horns and laying false scents. Molland writes that one of these HSA groups was led by a law student, Ronnie Lee, who formed his group in Luton in 1971. In 1972, Lee and a fellow activist, Cliff Goodman, decided more militant tactics were needed. They revived the name of a 19th-century RSPCA youth group, The Bands of Mercy, and set up the Band of Mercy, which attacked hunters' vehicles by slashing tires and breaking windows, calling their direct action "active compassion." Volunteers left notes on the vehicles explaining why they had been attacked, assuring the hunters that the attacks were not personal.

In 1973, the Band of Mercy learned that Hoechst Pharmaceuticals was building a research laboratory near Milton Keynes. On November 10, 1973, two activists set fire to the building, causing £26,000 worth of damage, returning six days later to set fire to what was left of it. It was the animal liberation movement's first known act of arson. Then, as now, it caused a split within the fledgling movement. In July 1974, the Hunt Saboteurs Association offered a £250 reward for information leading to the identification of the Band of Mercy, telling the press, "We approve of their ideals, but are opposed to their methods." In June 1974, two Band of Mercy activists set fire to boats taking part in the annual seal cull off the Norfolk coast, which Molland writes was the last time the cull took place. Between June and August 1974, it launched eight raids against animal-testing laboratories, and others against chicken breeders and gun shops, damaging buildings or vehicles. Its first act of "animal liberation" took place during the same period when activists removed half a dozen guinea pigs from a guinea pig farm in Wiltshire, which resulted in the owner closing her business, fearing further attacks

The movement is entirely decentralized, with no formal membership or hierarchy, the absence of which acts as a firebreak when it comes to legal responsibility. Volunteers are expected to stick to the ALF's stated aims when using its banner. Any direct action that contradicts these aims—and in particular the provision not to harm human or non-human life—may not be claimed as an ALF act:

• To inflict economic damage on those who profit from the misery and exploitation of animals.
• To liberate animals from places of abuse, i.e. laboratories, factory farms, fur farms etc., and place them in good homes where they may live out their natural lives, free from suffering.
• To reveal the horror and atrocities committed against animals behind locked doors, by performing nonviolent direct actions and liberations
• To take all necessary precautions against harming any animal, human and non-human.
• Any group of people who are vegetarians or vegans and who carry out actions according to ALF guidelines have the right to regard themselves as part of the ALF

ALF activists believe that animals should not be viewed as property, and that scientists and industry have no right to assume ownership of living beings who are each, in the words of philosopher Tom Regan, the "subject-of-a-life." In the view of the ALF, to fail to recognize this is an example of speciesism—the ascription of different values to beings on the basis of their species membership alone—which they argue is as ethically flawed as racism or sexism. They reject the animal welfarist position that more humane treatment is needed for animals; they say their aim is empty cages, not bigger ones. Activists argue that the animals they remove from laboratories or farms are "liberated," not "stolen," because they were never rightfully owned in the first place.

Although the ALF rejects physical violence, many activists deny that attacks on property count as violent action. Their argument for sabotage is that the removal of animals from a laboratory simply means they will be quickly replaced, but if the laboratory itself is destroyed, it not only slows down the restocking process, but increases costs, possibly to the point of making animal research prohibitively expensive. This, they argue, will encourage the search for alternatives. An ALF activist involved in an arson attack on the University of Arizona told No Compromise in 1996: "[I]t is much the same thing as the abolitionists who fought against slavery going in and burning down the quarters or tearing down the auction block ... Sometimes when you just take animals and do nothing else, perhaps that is not as strong a message."

Peter Singer, professor of bioethics at Princeton University, has argued that ALF direct action can only be regarded as a just cause if it is non-violent, and that the ALF is at its most effective when uncovering evidence of animal abuse that other tactics could not expose. He cites as an example the ALF raid on the University of Pennsylvania head-injury research clinic in 1984, during which footage shot by the researchers was removed, showing them laughing at conscious baboons as severe brain damage was inflicted on them. The university responded that the treatment of the animals conformed to National Institutes of Health (NIH) guidelines, but as a result of the publicity, the lab was closed down, the chief veterinarian fired, and the university placed on probation. Barbara Orlans, a former animal researcher with the NIH wrote that the case stunned the biomedical community, and is today considered one of the most significant cases in the ethics of using animals in research. Singer argues that if the ALF would focus on this kind of direct action, instead of sabotage, it would appeal to the "minds of reasonable people."

Philosopher Steven Best, a former ALF press officer, has coined the term "extensional self-defence" to describe actions carried out in defence of animals by human beings acting as "proxy agents." He argues that, in carrying out acts of extensional self-defence, activists have the moral right to engage in acts of sabotage or even violence. Extensional self-defence is justified, he writes, because animals are in too vulnerable and oppressed a position to fight back. Best argues that the principle of extensional self defence mirrors the penal code statues known as the "necessity defence," which can be invoked when a defendant believes that the illegal act was necessary to avoid imminent and great harm. In testimony to the Senate in 2005, Jerry Vlasak stated that he regarded violence against Huntingdon Life Sciences as an example of extensional self-defence.

Early Violence - The First Wave

Monaghan writes that, around 1982, there was a noticeable shift in the non-violent position, and not one approved by everyone in the movement. Some activists began to make personal threats against individuals, followed by letter bombs and threats to contaminate food, the latter representing yet another shift to threatening the general public, rather than specific targets.

In 1982, letter bombs were sent to all four major party leaders in England, including the prime minister, Margaret Thatcher. In November 1984, the first major food scare was carried out, with the ALF claiming in phone calls and letters to the media that it had contaminated Mars Bars—part of a campaign to force the Mars company to stop conducting tooth decay tests on monkeys. On November 17, the Sunday Mirror received a call from the ALF saying it had injected Mars Bars in stores throughout the country with rat poison. The call was followed by a letter containing a Mars Bar, presumed to be contaminated, and the claim that these were on sale in London, Leeds, York, Southampton, and Coventry. Millions of bars were removed from shelves and Mars halted production, at a cost to the company of $4.5 million. The ALF admitted the claims had been a hoax. Similar contamination claims were later made against L'Oréal and Lucozade.

The letter bombs to politicians were claimed by the Animal Rights Militia (ARM). The Mars Bar hoax is now also attributed by newspapers to the ARM, although the initial report by David Mellor, then a Home Office minister, to the House of Commons on November 19, 1984 was clear that it was the Animal Liberation Front who had claimed responsibility.

This is an early example of the shifting of responsibility from one banner to another, depending on the nature of the act, with the ARM and another nom de guerre, the Justice Department—the latter first used in 1993—emerging as names that activists used for direct action that violated the ALF's "no harm to living beings" principle. Ronnie Lee, who had earlier insisted on the importance of the ALF's non-violence policy, seemed to support the idea. An article signed by RL—presumed to be Ronnie Lee—in the October 1984 ALF Supporters Group newsletter, suggested that activists set up "fresh groups ... under new names whose policies do not preclude the use of violence toward animal abusers."

No activist is known to have conducted operations under both the ALF and ARM banners, but overlap is nevertheless assumed. Paul Wilkinson, a terrorism expert, has written that the ALF, the Justice Department, and the ARM are essentially the same, and Robert Garner of the University of Leicester writes that it would be pointless to argue otherwise, given the nature of the movement as a leaderless resistance. Robin Webb of the British Animal Liberation Press Office has acknowledged that the activists may be the same people: "If someone wishes to act as the Animal Rights Militia or the Justice Department, simply put, the ... policy of the Animal Liberation Front, to take all reasonable precautions not to endanger life, no longer applies."

From 1983 onwards, a series of fire bombs exploded in department stores that sold fur, with the intention of triggering the sprinkler systems in order to cause damage, although several stores were partly or completely destroyed In September 1985, incendiary devices were placed under the cars of Dr. Sharat Gangoli and Dr. Stuart Walker, both animal researchers with the British Industrial Biological Research Association (BIBRA), wrecking both vehicles but with no injuries, and with the ARM claiming responsibility. In January 1986, the ARM said it had placed devices under the cars of four employees of Huntingdon Life Sciences, timed to explode an hour apart from each other. A further device was placed under the car of Dr. Andor Sebesteny, a researcher for the Imperial Cancer Research Fund which he spotted before it exploded.

The nature of the ALF exposes its name to the risk of being used by activists who reject its non-violence platform, or by opponents conducting so-called "false flag" operations, designed to make the ALF appear violent. That same uncertainty provides genuine ALF activists with plausible deniability should an operation go wrong, by denying that the act was "authentically ALF".

Several incidents in 1989 and 1990 were described by the movement as false flag operations. In February 1989, an explosion damaged the Senate House bar in Bristol University, an attack claimed by the unknown "Animal Abused Society". In June 1990, two days apart, bombs exploded in the cars of Margaret Baskerville, a veterinary surgeon working at Porton Down, a chemical research defence establishment, and Patrick Max Headley, a psychologist at Bristol University. Baskerville escaped without injury by jumping through the window of her mini-jeep when a bomb using a mercury-tilt device exploded next to the fuel tank. During the attack on Headley, which New Scientist writes involved the use of plastic explosives, a 13-month-old baby passing by in a stroller suffered flash burns, shrapnel wounds to his back, and a partially severed finger.

No known entity claimed responsibility for the attacks, which were condemned within the animal rights movement and by ALF activists. Keith Mann writes that it did not seem plausible that activists known for making simple incendiary devices from household components would suddenly switch to mercury-tilt switches and plastic explosives, then never be heard from again. A few days after the bombings, the unknown "British Animal Rights Society" claimed responsibility for having attached a nail bomb to a huntsman's Land Rover in Somerset. Forensic evidence led police to arrest the owner of the vehicle, who admitted he had bombed his own car to discredit the animal rights movement, and asked for two similar offences to be taken into consideration. He was jailed for nine months. The Baskerville and Headley bombers were never apprehended

Violence - The Second Wave

From the mid 1990s onwards violence against property began to increase substantially after several high-profile campaigns closed down facilities perceived to be abusive to animals. Consort Kennels, a facility breeding beagles for animal testing; Hillgrove Farm, which bred cats; and Newchurch Farm, which bred guinea pigs, were all closed after being targeted by animal rights campaigns that appeared to involve the ALF. In the UK, the financial year 1991-1992 saw around 100 refrigerated meat trucks destroyed by incendiary devices at a cost of around £5 million. Butchers' locks were superglued, shrink-wrapped meats were pierced in supermarkets, slaughterhouses and refrigerated meat trucks were set on fire

In 1999, ALF activists became involved in the international Stop Huntingdon Animal Cruelty (SHAC) campaign to close Huntingdon Life Sciences (HLS), Europe's largest animal-testing laboratory. The Southern Poverty Law Center, which monitors U.S. domestic extremism, has described SHAC's modus operandi as "frankly terroristic tactics similar to those of anti-abortion extremists." ALF activist Donald Currie was jailed for 12 years and placed on probation for life in December 2006 after being found guilty of planting homemade bombs on the doorsteps of businessmen with links to HLS. HLS director Brian Cass was attacked by men wielding pick-axe handles in February 2001, an attack so serious that Detective Chief Inspector Tom Hobbs of Cambridgeshire police said it was only by sheer luck that they were not starting a murder inquiry. David Blenkinsop was one of those convicted of the attack, someone who in the past had conducted actions in the name of the ALF.

Also in 1999, a freelance reporter, Graham Hall, said he had been attacked after producing a documentary critical of the ALF, which was aired on Channel 4. The documentary showed ALF press officer, Robin Webb, appearing to give Hall—who was filming undercover and purporting to be an activist—advice about how to make an improvised explosive device, though Webb said his comments had been used out of context. Hall said that, as a result of the documentary, he was abducted, tied to a chair, and had the letters "ALF" branded on his back, before being released 12 hours later with a warning not to tell the police.

In June 2006, the ALF claimed responsibility for a firebomb attack on UCLA researcher Lynn Fairbanks. The Animal Liberation Press Office issued a statement saying that Fairbanks was conducting painful addiction experiments on monkeys. though Fairbanks herself said that she studies primate behaviour and does not do invasive research. A firebomb was placed on the doorstep of a house occupied by Fairbanks' 70 year-old tenant; according to the FBI, it was powerful enough to have killed the occupants, but failed to ignite. The attack was credited by the acting chancellor of UCLA as helping to shape the Animal Enterprise Terrorism Act. ALF spokesman Jerry Vlasak said of the attack on Fairbanks: "force is a poor second choice, but if that's the only thing that will work ... there's certainly moral justification for that." As of 2008, activists were increasingly taking protests to the homes of researchers, staging "home demonstrations," which can involve making noise during the night, writing slogans on the researchers' property, smashing windows, and spreading rumours to neighbours

In 1993, ALF was listed as an organization that has "claimed to have perpetrated acts of extremism in the United States" in the Report to Congress on the Extent and Effects of Domestic and International Terrorism on Animal Enterprises.It was named as a terrorist threat by the U.S. Department of Homeland Security in January 2005. In March 2005, a speech from the Counterterrorism Division of the FBI stated that: "The eco-terrorist movement has given rise and notoriety to groups such as the Animal Liberation Front, or ALF, and the Earth Liberation Front, or ELF. These groups exist to commit serious acts of vandalism, and to harass and intimidate owners and employees of the business sector." In hearings held on May 18, 2005 before a Senate panel, officials of the FBI and the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) stated that "violent animal rights extremists and eco-terrorists now pose one of the most serious terrorism threats to the nation." In the UK in 1998, terrorism expert Paul Wilkinson said that the ALF and its splinter groups were the "most serious domestic terrorist threat within the United Kingdom," and that the ALF is "very close" to killing someone.

The Southern Poverty Law Center has criticized Homeland Security for focusing on the Animal and Earth Liberation Fronts rather than on white supremacists, writing that, although ALF members use "frankly terroristic tactics" "for all the property damage they have wreaked, eco-radicals have killed no one—something that cannot be said of the white supremacists and others who people the American radical right." Senator James Jeffords said that the "Congress can't do much about individual extremists committing crimes in the name of ELF or ALF, but we can act to significantly enhance the safety of communities across the nation...ELF and ALF may threaten dozens of people each year, but an incident at a chemical, nuclear or wastewater facility would threaten tens of thousands. On January 20, 2006, as part of Operation Backfire, the U.S. Department of Justice announced charges against nine American and two Canadian activists calling themselves the "family," who are alleged to have engaged in direct action in the name of the ALF and ELF. The Department of Justice called the acts examples of "domestic terrorism." Environmental and animal rights activists have referred to the legal action as the Green Scare. The incidents included arson attacks against meat-processing plants, lumber companies, a high-tension power line, and a ski center, in Oregon, Wyoming, Washington, California, and Colorado between 1996 and 2001.