(CNN) Athletes have criticised the US Anti-Doping Agency's (USADA) decision to drop its charges against sprinter Christian Coleman following the advice of the World Anti-Doping Agency (WADA).
American Coleman -- the fastest man in the world this year -- had broken anti-doping rules by missing three drug tests in 12 months and was facing an automatic one-year ban.
But his case was dropped on a technicality over dates, sparking some athletes to declare the decision "unreal" and "crazy."
The 23-year-old is now free to compete at the World Athletics Championships which begin in Doha on September 28.
Coleman ran a world-leading time of 9.81 seconds in the Diamond League in California in June -- a time just 0.02 seconds slower than his personal best.
But he fell foul of WADA's "whereabouts" system, which requires athletes to let officials know where they will be for one hour every day, as well as details of overnight accommodation and training venues.
If an athlete fails to do so -- known as a "filing failure" -- three times over a 12-month period, they could face punishment.
Coleman's filing failures were recorded on June 6, 2018, January 16, 2019 and April 26, 2019, but under International Standard for Testing and Investigations (ISTI) guidelines, filing failures relate back to the first day of the quarter.
According to Coleman, his failure to update on June 6 should relate back to April 1, 2018 which is more than 12 months prior to his third filing failure on April 26, 2019.
"Consistent application of the global anti-doping rules is essential in every case," said USADA CEO Travis Tygart.
"We must approach every case with the primary goal of delivering fairness to athletes under the rules and providing transparency and consistency in order to build their trust and support for the anti-doping system.
"Every athlete is entitled to a presumption of innocence until their case is concluded through the established legal process. This is certainly the case for Mr. Coleman, who has been found by USADA not to have committed a Whereabouts Violation and is fully eligible to compete under the rules."
However, two-time Olympian Kara Goucher called the decision "unreal," while Paralympic silver medalist Ali Jawad labeled it "crazy."
"Imagine breaking a really big rule with big consequences, only to discover a new rule which makes prior rule useless," Goucher said on Twitter.
"So future athletes with whereabouts failures - 3 missed tests in a 12-month period, with WADAs approval, can be changed to a 14-month period. No worries. Unreal."
Callum Skinner -- a 2016 Olympic cycling gold medalist -- thinks changes need to be made to the system, citing Coleman's contention that, "I'm not a guy who takes any supplements at all, so I'm never concerned about taking drug tests."
"If only he applied such a principled stance to making himself available for testing. This loophole needs to be closed, use testing date not the 1/4. 3 missed tests 12 months = ban," Skinner wrote on Twitter.