(FILES) This file picture taken on February 10, 2008 in Sheffield shows British sprinter Dwain Chambers reacting after winning the Mens 60m final during the world trials and UK championships at the English Institute for Sport. Dwain Chambers has started court proceedings against the British Olympic Association (BOA) in a bid to enable him to compete at next month's Beijing Olympics, it was announced Thursday July 3, 2008. The 30-year-old is currently banned from competing at any Olympics by a BOA bylaw which prevents all those found guilty of doping offences representing the country at a Games, even if they have served a drugs ban, unless they can prove "mitigating circumstances". AFP PHOTO/Andrew Yates/FILES (Photo credit should read ANDREW YATES/AFP/Getty Images)