The special theory of relativity (STR) is perhaps one of the most controversial theories in the history of science. Countless arguments have been made against STR by researchers, prominent scientists and lay persons. This paper reveals for the first time that most of the confusions arise from incomplete development of the theory, rather than from possible fundamental contradictions. This has caused STR not being not fully understood even by professional physicists, who have been applying it inconsistently. For example, the GPS is being cited wrongly to support STR. Proponents and opponents of relativity theory have been arguing over an incomplete theory for more than a century. In this paper we introduce a new concept called ‘proper space time coordinates of events’ that will complete the STR, clearing the contradictions and paradoxes. It is shown that the existing concepts of proper length and proper time are incomplete. The new formulation not only results in a complete version of STR that is mathematically and logically consistent, but also, ironically, leads to its ultimate disproof. It turns many of the light speed experiments, such as the GPS and the Lunar Laser Ranging (LLR,), against STR. These add to the already existing experimental evidences contradicting with relativity theory, such as the Silvertooth, the Marinov and the Roland De Witte experiments.