The number of inspectors has recently been increased from an average of 14.5 inspectors in 2023 to 22 in 2026 following an assessment of the resource required for the Animals in Science Regulation Unit to meet its purpose and strengthen the regulatory system. The 3Rs, replacement, reduction and refinement, are a legal requirement under the Animals (Scientific Procedures) Act 1986 and must be fully applied in every project involving the use of animals in science. Applicants must demonstrate consideration of the 3Rs before submission, and all applications are assessed by Home Office Inspectors to assure that no practicable non-animal alternatives exist, that animal numbers are minimised, and that methods are refined to reduce suffering. This assessment is supported by continuous scrutiny after a licence is granted. ASRU conducts announced and unannounced audits, reviewing records and practices to monitor the continually application of the 3Rs and that licence conditions remain appropriate. In November 2025, the Government published “Replacing animals in science: a strategy to support the development, validation and uptake of alternative methods”. This strategy includes commitments to improve regulatory confidence and acceptance of alternative methods to animal testing, including plans to establish a UK Centre for the Validation of Alternative Methods (UKCVAM) to help coordinate validation activity and facilitate engagement between policy makers, regulators, industry end users and alternative method developers. This strategy includes clear time-bound targets for the reduction of animals used in science. In addition, the National Centre for Replacement, Refinement and Reduction is scheduled to provide recommendations to the Home Office to enhance the project licence application form for undertaking research involving animals. This will include advice aimed at strengthening the evaluation of replacement strategies.