South Africa's Caster Semenya can continue to compete pending her appeal, after a Swiss court rejected the IAAF's request to re-impose its new rules on the 800m Olympic champion.
Semenya is appealing to Switzerland's Federal Supreme Court (SFT) against the world governing body's rules restricting testosterone levels in female runners.
The IAAF wanted to reverse the SFT's decision to suspend the restrictions pending Semenya's appeal, but her lawyers said the request was rejected.
The new rules state that Semenya and other athletes with differences of sexual development (DSD) - must either take medication in order to compete in track events from 400m to the mile, or change to another distance.
Three-time world champion Semenya said: "No woman should be subjected to these rules. I thought hard about not running the 800m in solidarity unless all women can run free. But I will run now to show the IAAF that they cannot drug us."
In a statement, her lawyers said: "After considering the IAAF's arguments, the Court has now determined in a second order that the IAAF's request failed to set out any reason or change in circumstance that would justify a reconsideration of the prior order.
"This means that Caster remains permitted to compete without restriction in the female category at this time."
The IAAF said it "continues to comply with the Swiss Federal Tribunal's order dated 31 May to suspend the DSD Regulations in as far as they apply to the appellant".
Double 800m Olympic champion Semenya has been named in South Africa's preliminary squad for the World Championships in Qatar later this year.
She has only been entered in the 800m and her participation depends on the outcome of her appeal.
Semenya said she has been prevented from competing in the 800m at the Diamond League in Rabat, Morocco on Sunday.
Her lawyers said: "Caster is currently seeking clarity on the specific reasons for that decision, and she urges the IAAF to ensure its member federations comply with the law and the Supreme Court's orders."
The IAAF says it does not organise Diamond League meetings and "entry for any athlete into a Diamond League meeting is by invitation only from the meeting organiser".
BBC Sport has contacted the Diamond League and the Royal Moroccan Athletics Federation for comment.