SAN FRANCISCO -- Major League Baseball's players union said Thursday it would challenge a federal appeals court's decision to give prosecutors access to the names and urine samples of about 100 players who tested positive for steroids in 2003.

Donald Fehr, executive director of the Major League Baseball Players Association, said if Wednesday's decision by the 9th U.S. Circuit Court of Appeals "is allowed to stand it will effectively repeal the Fourth Amendment for confidential electronic records."

Fehr said he was consulting with union attorneys to "determine what our next step should be in our fight to protect the constitutional rights, including the basic right to privacy, of our members."

Options include asking the San Francisco-based appeals court to rehear the case with the same three judges, petitioning the court to hear the case with 15 judges or appeal to the U.S. Supreme Court. Any appeal, even if unsuccessful, could delay the government from getting the records for months or more.

The court's 2-1 ruling could help authorities pinpoint the source of steroids in professional baseball. It could also bolster the perjury case against Giants slugger Barry Bonds, who is under investigation for telling a grand jury he never knowingly used performance-enhancing drugs.

Michael Rains, Bonds' attorney, disagreed. "It doesn't help their case against him," he said.

The samples were collected at the league's direction as part of a survey to gauge the prevalence of steroid use. Players and owners agreed in their labor contract that the results would be confidential.

U.S. Attorney Kevin Ryan of San Francisco, where the government's steroid probe is centered, praised the appellate court's finding that the government's "use of grand jury subpoenas were reasonable."

The testing was part of baseball's effort to determine whether a stricter drug-testing policy was needed. Because 5 percent or more of the tests for steroids came back positive, it automatically triggered the start of testing with penalties in 2004.

The players' union sued to keep the government from accessing the records, saying the seizures violated the players' constitutional rights.

Wednesday's 120-page decision overturned a lower court that sided with the players. U.S. District Judge Susan Illston of San Francisco had quashed the subpoenas, ruling they constituted harassment and were unreasonable.

The government's investigation of the Bay Area Laboratory Co-Operative, a now-defunct Burlingame supplements lab at the center of the steroid scandal, already has resulted in guilty pleas from BALCO president Victor Conte, Bonds' personal trainer Greg Anderson, BALCO vice president James Valente, chemist Patrick Arnold and track coach Remi Korchemny.

Indictments are pending against cyclist Tammy Thomas and track coach Trevor Graham.