Animals (Scientific Procedures) Act 1986
The Animals (Scientific Procedures) Act 1986 (A(SP)A 86) is an Act of the Parliament of the United Kingdom (1986 c. 14) passed in 1986, which regulates the use of laboratory animals in the UK. The Act permits experiments to be carried out on animals, including procedures involving vivisection, if certain criteria are met. 
The British Union for the Abolition of Vivisection argues that the Act is designed to protect researchers from prosecution for cruelty, rather than to protect the animals themselves.  However, a select committee inquiry described the Act as the "tightest system of regulation in the world." 

# Background
Prior to A(SP)A 86, the use of animals in the UK was regulated by the 1876 Cruelty to Animals Act, which enforced a licensing and inspection system for vivisection. Animal cruelty is regulated by the 1911 Protection of Animals Act, which outlaws the causing of "unnecessary suffering", though this law does not apply experiments licensed under the 1986 Act. 

# Scope
The 1986 Act regulates procedures, defined as animal experiments that could potentially cause "pain, suffering, distress or lasting harm", to protected animals, encompassing all living vertebrates other than humans. A 1993 amendment to the Act included a single invertebrate species, Octopus vulgaris, as a protected animal. The Act applies only to protected animals from halfway through their gestation or incubation periods (for mammals, birds and reptiles) or from when they capable of independent feeding (for fish, amphibians and, latterly, octopuses).

# Licences
A(SP)A 86 is characterised by three levels of regulation - person, project, and place. The 'person' level is achieved by the granting of a personal licence (PIL) to a researcher wishing to carry out regulated procedures on a protected animal. Having undergone a defined sequence of training, a researcher can apply for and be granted a PIL permitting specified techniques to be carried out in named species of animals. The 'project' level of regulation is governed by the granting of a project licence (PPL) to a suitably qualified senior researcher. The PPL will detail the scope of the work to be carried out, the likely benefits that may be realised by the work, and the costs involved in terms of the numbers and types of animals to be used. Typically a large and detailed document, the PPL precisely defines which techniques may be applied to particular animals and for what purpose. Finally the place where regulated procedures are carried out is controlled by the granting of a "certificate of designation" (PCD), which will list which rooms in the establishment are permitted to be used for certain techniques and species.

# Opinion
The British Union for the Abolition of Vivisection has criticized the Act, arguing that its main function is not to protect animals, but to protect researchers by permitting them to carry out acts that would be illegal outside a laboratory setting. BUAV writes that: "Under the 1986 Act, it is still perfectly legal for an animal in a laboratory to be unnaturally caged for its entire life; poisoned; deprived of food, water or sleep; applied with skin and eye irritants; subjected to psychological stress; deliberately infected with diseases such as cancer and AIDS; brain damaged; paralysed; surgically mutilated; irradiated; burned; gassed; force fed, electrocuted and killed." 
Patricia Hewitt, then British Secretary of State for Trade and Industry, argues that the Act is among "the strongest laws in the world to protect animals which are being used for medical research." 
A 2002 House of Lords select committee inquiry compared the Act to legislation from France, the U.S., and Japan. The report concluded that "virtually all witnesses agreed that the UK has the tightest system of regulation in the world" and that it is "the only country to require an explicit cost/benefit assessment of every application to conduct animal research."   Note that in this case, costs are explicitly in terms of animal suffering, not the financial cost to the experimenters.