Stevens finished seventh in the women's 200 metres at Rio 2016, but is not eligible to compete again until August 16 2021.

The re-arranged Tokyo Olympics finish on August 8.

Stevens missed anti-doping tests in February, August and November of 2019.

Three missed tests in a 12-month period equates to an anti-doping rule violation and ordinarily a two-year ban for an athlete's first offence, but the AIU panel reduced Stevens' period of ineligibility by six months in light of mitigated circumstances presented by Stevens in her defence.

At the time of the third missed test, the athlete had updated her phone number to avoid harassment - which included threats made to her fiancé's life - but had not informed the anti-doping authorities.

This meant that, when the sample-collection officer was unable to access the building where Stevens was supposed to be, they were not able to contact the athlete.

The panel deemed this "unambiguously negligent", but did express sympathy for Stevens' predicament.

The first missed test was not contested; there was restricted access to the location where Stevens was supposed to be, meaning the doping-control officer could not conduct a test.

For the second missed test, a doping-control officer rang the athletes' phone five times and thrice knocked on their door, but there was no response.

Stevens' explanation - which included a flat phone battery and the position of the bedroom where she was asleep - was deemed by the panel to be "based on a string of excuses that we have not found persuasive."

The 18-month ban has been backdated to February 17 of this year, the date of the athlete's request for an expedited hearing.

Stevens came fifth in the 200m final at the 2017 World Athletics Championships in London.

She is not the only high-profile American sprinter to have amassed three whereabouts failures in a 12-month window as Christian Coleman, the reigning men's 100m world champion, has been provisionally suspended by the AIU for the same offence.