Story highlights Dwain Chambers is reading and reviewing the decision, his agent says

The ruling clears the way for more athletes to compete in 2012

Two U.S. athletes were hoping it would be declared invalid

The rule affects athletes suspended for more than six months for doping

Athletes suspended for doping cannot be barred from competing in the next Olympics if they have served their ban, the highest court in international sports ruled Thursday.

The so-called "Osaka Rule" is "invalid and unenforceable," the Court of Arbitration for Sport ruled.

The move clears the way for more athletes to compete in London in 2012, including Americans LaShawn Merritt, a runner, and swimmer Jessica Hardy.

The International Olympic Committee's Rule 45, also called the Six-Month Rule, bars athletes with six-month suspensions from the next Games.

The U.S. Olympic Committee challenged the rule earlier this year before the Court of Arbitration for Sport, and the Swiss-based court issued its decision.

Critics complain the rule means those who have served their suspensions are effectively being punished twice for the same offense.

British sprinter Dwain Chambers, who was permanently banned from the Olympics by his country's Olympics committee over doping, is studying the ruling, his agent said.

"Dwain and I just want the opportunity to read, digest and review the reasoning behind the decision," Siza Agha told CNN.

While the court's decision will affect all athletes facing a ban on competing at the Games because of the rule, the U.S. committee was seeking specifically to resolve the fate of Merritt and Hardy.

Merritt, 25, won two gold medals at the 2008 Beijing Games, but was suspended for 21 months after testing positive for DHEA, a steroid. He returned shortly before the World Outdoor Championships this summer.

Merritt has said the use of the banned substance was the inadvertent result of taking an over-the-counter "male enhancement" pill "and occurred at a time that he was neither seriously training nor competing."

Hardy, 24, tested positive in July 2008 for the banned substance Clenbuterol just a month before the Beijing Olympics and was suspended for a year starting August 1, 2008. Her suspension meant she was unable to compete at what would have been her first Olympic Games.

Hardy said she did not take the substance on purpose, but said it was included and not labeled in a contaminated nutritional supplement, according to USA Swimming, the national governing body for the sport.

Howard Jacobs, the attorney for Merritt, Hardy and the U.S. committee, said Wednesday they hoped the court would decide that the international committee's rule is invalid.

"I think the USOC wanted certainty with respect to which athletes would be able to compete in the 2012 Olympics rather than waiting until the last minute," Jacobs told CNN. "Certainly, I think the LaShawn Merritt case provided some impetus to having discussions with the IOC regarding this case."

IOC Director-General Christophe De Kepper said earlier this year that the ruling "will provide certainty in the lead-up to the London 2012 Olympic Games."