Anti-doping tests are always one step behind the they look for.
A test can only detect what somebody has already described.
New therefore pass unnoticed until a sample is stored and .
Storing samples for ten years has caught athletes long after a medal.
The threat of a later test may more than the test itself.
Testing also lands unevenly across sports and countries.
A well-funded tests often, and its athletes are cleared often.
A poorer one tests rarely, and falls on everyone in it.
That damages clean athletes most.
Some argue that the whole system should be abandoned as unwinnable.
The counter-argument is not about catching everyone.
It is about keeping the cost of cheating high enough to matter.