Babe Ruth, on 14 October 2012 - 01:41 PM, said:
Exactly right.
The question seems to be why are some performance enhancing substances OK, while some are not?
You got that wrong: all performance enhancing substances are banned from sports, it is just that some are detectable now (used by the less wealthy or intelligent) and some will be detectable in the future. What has changed is the rules where now biological samples are preserved until a statute of limitations and checked for forbidden substances in the future as soon as the test becomes available.
That way the anti-doping agencies hope to take away the incentive of creating new drugs to enhance performance of what can be achieved by natural training.
What does exist is a list of known substances that are forbidden with exemptions when they may be used (i.e. certain illnesses on part of the athlete) and common food components (i.e. caffeine, lactose, glucose) that, while increasing performance, are not banned if within limits. That is not quite the same as having a list of allowed and disallowed doping.