IOC president Thomas Bach has insisted that sprinter Justin Gatlin has the "right to compete" after serving his suspension for a doping offence.
Since his return to the sport, Gatlin has established himself as Usain Bolt's main competition in the 100m, and despite questions being raised about his participation, Bach admits that there is little that can be done.
Bach told reporters: "I would still support a lifetime ban, but legally it's just not possible. A lifelong ban would not stand any kind of legal challenge so we have to accept that.
"As for [Gatlin], if you have an athlete who has served his suspension then he has the right to compete. It's a legal question not to be able to take stricter sanctions, a question of human rights."
The World Athletics Championships get underway on Saturday, with the 100m being run over the weekend.
