Evolution is not a scientific theory. It fails the requirement of falsifiability that is the litmus test for judging whether an investigation is scientific.
The modern scientific method is defined in terms of hypotheses, theories and laws. The difference between each is the level of acceptance in the scientific community. What they all have in common is that they must be falsifiable. This means that it must be possible to run an experiment that would prove the theory (or hypothesis or law) wrong, if it were not true.
