The Hunt Saboteurs Association (HSA) is an organisation that uses direct action to stop fox hunting, founded in 1963. The practices of hunt saboteurs are controversial, risks are taken, and hunt saboteurs have been seriously injured.  
In 1964 John Prestige founded the Hunt Saboteurs Association in Brixham, England, after being assigned to report on the Devon and Somerset Staghounds, where "he witnessed the hunters drive a deer into a village and kill her."  Designed to "violently oppose blood sports,"  the HSA eschewed parliamentary reforms and instead went directly out onto hunting grounds to do everything they could, sometimes breaking the law and sometimes being arrested, to prevent the killing of British wildlife. "Within a year, HSA groups appeared across England in Devon, Somerset, Avon, Birmingham, Hampshire and Surrey. Ronnie Lee, founder of the animal rights group Band of Mercy (and later the Animal Liberation Front), began his activism within an HSA group in Luton, England. HSA now operates throughout Europe and North America.
The HSA uses tactics such as: hunting horns and whistles to misdirect hounds, spraying scent dullers, laying false trails, and locking gates to interfere with the progress of a hunt. In the mid-1990s members used a "gizmo" (a portable cassette tape player linked up to a megaphone or other portable amplification equipment) to play the sound of hounds in cry, causing the dogs to break off the chase. These are examples of "non violent direct action tactics".
The HSA has expanded into Europe, the United States and Canada, and have adapted their tactics depending on the type of hunting being disrupted. The HSA now routinely disrupt deer, waterfowl, turkey, mink, and hare hunts, as well as angling and other types of fishing. As a result, numerous states have passed laws forbidding the disruption of legal hunting activities.
HSA UK publishes a quarterly journal, Howl.
A public order act was created to help control HSA members on private land. Part V Criminal Justice and Public Order Act 1994 (CJPOA) Section 68(1) created offences in connection with trespass by hunt saboteurs, including giving police officers the power to "direct trespassers on land (who are there with the common purpose of residing there for any period) to leave the land where the occupier has taken steps to ask them to do so, and either:they have damaged the land; or they have used threatening, abusive or insulting behaviour to the occupier, the occupier's family, employees or agents; or between them they have 6 or more vehicles on the land".
The Act also created the offence of aggravated trespass which was formed (in part) to give the police power over HSA activists: "a person commits the offence of aggravated trespass if he trespasses on land in the open air and, in relation to any lawful activity which persons are engaging in or are about to engage in on that or adjoining land in the open air, does there anything which is intended by him to have the effect: a) of intimidating those persons or any of them so as to deter them or any of them from engaging in that activity, b) of obstructing that activity, or c) of disrupting that activity".