The importance placed on risk avoidance in our society has resulted in a broad range of regulations intended to guarantee safety of products such as pharmaceuticals and chemicals. Many of these regulations rely on animal tests. As a result, about 25% of the animal experiments in Europe are done for regulatory purposes. There are many initiatives that aim to replace, reduce, or refine laboratory animal use, but the regulatory acceptance and use of 3R models lags behind. The central question of this study is: "Which variables influence the regulatory acceptance and use of 3R models and in what way?" Regulatory acceptance is seen as one of the biggest hurdles 3R models face, but the rationale behind this is still underexplored. This study is an approach to filling that gap by combining opinions from experts in the field with literature on technology acceptance and risk regulation, resulting in a model of the variables that determine the process of the regulatory acceptance and use of 3R models.