The German Animal Welfare Act defines animal experiments as interventions or treatments on animals for experimental purposes, if these are associated with possible pain, suffering or harm. This includes genetic modifications of the genome and the breeding of genetically modified animal lines. Animal experiments are primarily used to answer scientific questions. These include basic research, the study and treatment of human and animal diseases, and regulatory safety and tolerability testing of drugs and chemicals. There are also animal experiments that are not directly related to a scientific question. These include procedures or treatments on live animals for education and training purposes, particularly in laboratory animal training and veterinary medicine. It also includes the production and propagation of substances or organisms needed for research, such as antibodies or parasites. If an animal is used solely for the removal of organs, cells or tissues after it has been killed, this is not considered animal experimentation under the Animal Welfare Act.

Animal experiments may only be designed and performed by persons with the appropriate professional qualifications. These include scientists in the fields of agriculture, veterinary medicine, human medicine and dentistry, and biologists specialising in zoology. In addition, they must have officially recognised proof of expertise through specialised training. Persons with a qualifying qualification, such as biological-technical assistants or laboratory animal technicians, may also be involved in animal experimentation if they have the necessary expertise. Proof of these qualifications is a basic requirement for the authorisation of an animal experiment and is checked by the competent authorities.

Animal experiments may only be carried out if they have been authorised by the competent authorities. The application for authorisation is extensive and is at least twelve pages long, even if left blank. Scientists must provide a comprehensive scientific and ethical justification for the proposed experiment. They must explain what new knowledge the animal experiment will provide, that the question is novel and has not been answered by previous animal experiments. It is particularly important to demonstrate that the research objective can only be achieved by animal testing. This requires thorough preparation and careful consideration of the potential harm to the animals. In accordance with the 3Rs principle (replacement, reduction, refinement), it must also be demonstrated that the test cannot be replaced by alternative methods (replacement), that the number of animals used is reduced to the minimum necessary (reduction) and that the distress to the animals is minimised (refinement). In addition, there are detailed legal requirements at both national and EU level for the housing and care of laboratory animals and for animal testing in agricultural research.

If researchers are absolutely dependent on animal experiments for their research, they submit an application for authorisation to the competent authority in their district, county or state. The application must include evidence that the technical and staffing requirements for the project are met: There must be a sufficient number of qualified staff at the institute, as well as sufficient space for housing the animals. The application must also include a statement from the animal welfare officer. Any questions that may arise can be clarified in a dialogue between the researcher and the animal welfare officer before the application is submitted to the authorities. This ensures that the application meets high quality standards before it is submitted for approval. The licensing authority then checks that the application is complete and that the research project is comprehensible. It is assisted by an independent advisory committee (Section 15 TierSchG). At least one third of the members of the committee are nominated by animal welfare organisations. In addition, the Commission is made up of expert veterinarians, doctors and scientists. All members serve on a voluntary basis. They advise the licensing authority on the application by issuing a recommendation. By law, the licensing process should be completed within 40 days. If the authority is satisfied that all requirements have been met, it authorises the animal experiment. This can be done with or without conditions (change in number of animals or choice of methods).

Every institution and company that carries out animal experiments must appoint one or more animal welfare officers and an animal welfare committee. Both bodies are required to advise the institution, particularly with regard to animal welfare. The Animal Welfare Officers are also required to ensure compliance with regulations, conditions and requirements in the interest of animal welfare and to comment on any application for approval of an experimental project. In this way, they assist scientists in preparing an application. They are available to answer questions and provide feedback on where researchers may need to improve the content and methodology of their application. The application, together with the opinion, is then forwarded to the competent regulatory authority. During the experiments, the Animal Welfare Officers remain in close contact with the researchers and animal caretakers to work on possible improvements. The Animal Welfare Officers are not bound by instructions in the performance of their duties. Each application for an experimental project is reviewed by the licensing authority, which in Lower Saxony is the State Office for Consumer Protection and Food Safety (Laves). The authority is assisted by an independent commission (the so-called §15 TSchG Commission). In Lower Saxony, the licensing authority is also the inspection authority. Inspections are usually carried out at least once a year. Ongoing experimental projects, the animals in the facility itself and completed projects are inspected. Particular attention is generally paid to documentation.

There are strict legal requirements for the welfare of laboratory animals, including room size, temperature, ventilation, noise levels and lighting. There must also be constant supervision of the animals by trained staff. In particular, animal welfare officers are responsible for ensuring compliance. These are also regularly monitored externally by the competent authority (Laves). However, scientists not only comply with legal requirements by keeping animals in an animal-friendly environment, they also have a vested interest in providing the animals with optimal housing conditions. This is partly for ethical reasons and partly for practical ones: Researchers can only obtain meaningful results from their experiments if the animals are exposed to as little stress as possible and are well cared for. Animal welfare also means providing an environment that meets the social and psychological needs of the animals.