Logical inference approach to relativistic quantum mechanics: derivation   of the Klein-Gordon equation
  The logical inference approach to quantum theory, proposed earlier [Ann. Phys. 347 (2014) 45-73], is considered in a relativistic setting. It is shown that the Klein-Gordon equation for a massive, charged, and spinless particle derives from the combination of the requirements that the space-time data collected by probing the particle is obtained from the most robust experiment and that on average, the classical relativistic equation of motion of a particle holds. 
H. C. Donker, M. I. Katsnelson, H. De Raedt, K. Michielsen
quant-ph