A transformation law for the space and time coordinates between two reference systems is deduced from the hypothesis of a privileged frame. No experiment performed up till now can distinguish them from Lorentz transformations.
Though the problems of realism and locality in physical theories is at least as old as modern quantum mechanics, the interest for the subject decreased considerably after its great achievements. However, in the last decades, a very important research has been developed in this line, and we can safely say that neither the idea of reality nor the locality have been eliminated in physics, although this fact is still unknown for the majority of the scientific community. Von Neumann's theorem on the theoretical side, and Aspect's experiment on the experimental one, have created this misunderstanding. The construction of explicit models have clarified highly the scope of these results. But the construction of a model is not only important for refutal purposes, of course. A model tries to represent how Nature works, being of fundamental importance when one wants to deepen it and to really understand it.