Los Angeles (AFP) -
Sha'Carri Richardson will play no part in the Olympics after being left out of the United States' 4x100m relay squad, USA Track and Field (USATF) confirmed on Tuesday.
Richardson had been ruled out of competing in the individual 100m in Tokyo after receiving a 30-day ban for testing positive for marijuana following her victory at the US trials last month.
But the prospect of competing as a member of the relay team had been left open, with Richardson's suspension ending before the opening rounds of the discipline get under way in Tokyo.
USATF rules allowed for the 21-year-old to be selected as one of two coach's picks alongside the top four finishers from the women's 100m final at the US trials.
However, that door was slammed shut by USATF on Tuesday after 2016 Olympic 4x100m relay gold medalist English Gardner and Aleia Hobbs were named as the two discretionary picks to complete the six-strong relay pool.
In a statement, USATF expressed sympathy for Richardson's case but said it had a responsibility to 'maintain fairness' for all athletes.
'First and foremost, we are incredibly sympathetic toward Sha'Carri Richardson's extenuating circumstances and strongly applaud her accountability - and will offer her our continued support both on and off the track,' USATF said.
'While USATF fully agrees that the merit of the World Anti-Doping Agency rules related to THC (marijuana) should be reevaluated, it would be detrimental to the integrity of the US Olympic Team Trials for Track & Field if USATF amended its policies following competition, only weeks before the Olympic Games,' it added.
'All USATF athletes are equally aware of and must adhere to the current anti-doping code, and our credibility as the National Governing Body would be lost if rules were only enforced under certain circumstances.'
- 'Emotional pain' -
Newspaper USA Today reported Gardner and Hobbs were told of their selection in the US team before Richardson accepted a reduced one-month suspension for her doping case.
That meant that adding Richardson to the squad with one of the discretionary places would have required either Gardner or Hobbs to be bumped from the team.
Richardson's failed drugs test shocked the world of athletics after it was confirmed by the United States Anti-Doping Agency last Friday.
Richardson is one of the rising stars of track and field and had been regarded as a potential gold medalist at the Olympics.
The charismatic Texan later told NBC television that she had taken marijuana to cope with a 'state of emotional pain' after learning of the death of her biological mother during the US trials last month in Eugene, Oregon.
'I would like to say to my fans, my family and my sponsors I apologize,' Richardson said. 'I apologize for the fact that I didn't know how to control my emotions or deal with my emotions during that time.'
Richardson's case prompted an outpouring of support from fellow athletes and celebrities, with many questioning anti-doping rules which prohibit marijuana use in the sporting world.
'This is trash,' US women's soccer star Megan Rapinoe wrote on Twitter. 'Standing with (Richardson) 100%. This has BEEN outdated.'
US track and field legend Michael Johnson also questioned the suspension.
'I don't know why marijuana is banned. Maybe a good reason. Maybe not,' tweeted Johnson, a four-time world champion and two-time Olympic champion at 400m and former world and Olympic 200m champion.
'I know how it feels to lose a parent. Indescribable pain! I'm from the same neighborhood as (Richardson) Tough place! I wish people would stop calling her and this ban stupid unless you know the reason for both.'