“I don’t think it was O.K. for them to pass the buck,” Ms. Williams said of the committee’s deference to sports organizations. “If there are Russian athletes who do meet the criteria, it’s going to be very hard for another athlete to go up against them.”
Pressure to discipline Russia had mounted in recent months. Russia’s Olympic weight lifting team and entire Paralympic team are facing a ban, and the country’s track and field team was barred by that sport’s governing body in June, a decision that withstood a court challenge last week.
Track and field officials had allowed Russian athletes to petition to compete, presuming athletes guilty rather than innocent. Over the last month, they rejected more than 60 applications and approved just two — including one from a Russian whistle-blower, the middle-distance runner Yuliya Stepanova, who spoke out against widespread doping in Russia after she herself was caught with an infraction; she has been branded a traitor by Russian officials.
On Sunday, Olympic officials rejected a request by Ms. Stepanova to participate in the Olympics as a neutral athlete rather than for Russia. The Olympic committee said it would not accept the entry of any Russian athlete with a prior drug violation, even if a penalty had been served in full.
“She put her life on the line,” Ms. Williams said, expressing disappointment at that decision.
Joseph de Pencier, chief executive of the Institute of National Anti-Doping Organizations, a trade group, called Sunday “a sad day for clean sport,” criticizing the Olympic Committee for its choice to outsource decisions and its failure to approve the whistle-blower’s request.
Katie Uhlaender, a winter Olympian, wondered about the implications for the Winter Games held in 2014 in Sochi, Russia. The recent investigation confirmed that Russian officials tampered with doping samples at Sochi, where Ms. Uhlaender placed fourth in the women’s skeleton competition, behind a Russian who won the bronze medal but was identified as among those whose steroid-laced urine samples were surreptitiously made to appear clean.
“Are they going to let Sochi be swept under the rug?” Ms. Uhlaender said Sunday. “The Russians have a lot of money, and the sports federations don’t. We’re looking for leadership to take a hard line.”
The Olympic board’s deliberations stemmed from a confession by the longtime director of Russia’s antidoping lab, Grigory Rodchenkov, who told The New York Times last spring how Russian officials had perpetrated one of the most elaborate doping programs in sports history. He shared spreadsheets of the athletes who had doped, along with the recipe for a three-drug cocktail of steroids and liquor he devised ahead of the 2012 Summer Games in London.
When Russia hosted the 2014 Olympics, Dr. Rodchenkov said, the country saw it as an opportunity to manipulate lab results and dope throughout competition, prompting him and Russia’s intelligence service to tamper with athlete samples nightly at the Games.
“It was very serious work — deliberate, structured, the best hands in Russia,” Dr. Rodchenkov said, reflecting on the scheme with pride for having successfully carried out complex orders without detection.
Dr. Rodchenkov suggested that Russia be barred from the Rio Games.
“If you’re fighting doping, Russia should be withdrawn from the Olympics,” he said in May in Los Angeles, where he fled with the help of a filmmaker, Bryan Fogel, whom he had been advising on a doping regimen for a documentary.
The World Antidoping Agency, which commissioned an investigation into Dr. Rodchenkov’s account, subsequently recommended to the Olympic committee that Russia be barred. Last week, the Canadian lawyer who conducted that inquiry said that forensic evidence, computer metadata and corroborating interviews had confirmed the schemes.
Russian officials, however, have continued to reject the whistle-blower’s accounts. In presenting Russia’s case to the Olympic committee before its decision Sunday, the head of Russia’s Olympic Committee, Alexander Zhukov, said that Dr. Rodchenkov was a man of “very questionable reputation” and that his testimony could not be credible, given that he was the “central figure in the criminal scheme that he had created.”
Mr. Zhukov urged the Olympic committee not to become “hostages of geopolitical pressure,” echoing statements by Mr. Putin that scrutiny of Russia’s doping record was politically motivated.
Dr. Rodchenkov said that although he thought all nations were guilty of doping, it was fair to pay particular attention to Russia, as the I.O.C. did Sunday.
“At such a level of state involvement, no other country could do this,” he said in May. “Only such a country like Russia. Thanks to God we can now speak. Sorry about Russia, but I am watching from the silos with all of these missiles.”