Banned Olympic sprint champion Justin Gatlin filed a lawsuit in a last-ditch effort on Monday to compete at the US Olympic athletics trials in less than three weeks.

In this Sept. 23, 2005 file photo, Olympic champion Justin Gatlin races in the men's 100-meter event during the Daegu International Athletics Competition in Daegu, south of Seoul, South Korea. [Agencies]

The complaint alleges that penalizing Gatlin for a 2001 doping violation, which involved medication he was taking for attention deficit disorder, violates the Americans with Disability Act.

Gatlin's lawyer, Joe Zarzaur, said they will request an injunction to allow him to compete at the trials, which begin on June 27 in Eugene, Oregon. He said he did not know when the case would be heard.

The suit was filed in US District Court in Gatlin's hometown of Pensacola, Florida.

On Friday, the Court of Arbitration for Sport upheld a four-year doping ban against the reigning Olympic 100-meter champ. Gatlin asked CAS to rescind the 2001 doping violation, which he had hoped would reduce his penalty to a two-year ban, allowing him to compete at the trials.

Instead, CAS rejected that argument and changed the start of Gatlin's ban to July 25, 2006, the day he voluntarily accepted his provisional suspension, instead of May 25, 2006. So he wouldn't be reinstated before the trials even if his ban had been reduced from four years to two.

Zarzaur said he also would ask the court to change the dates of the doping ban.

The 26-year-old Gatlin, who insists he never knowingly took performance-enhancing drugs, tested positive for excessive testosterone at the Kansas Relays in 2006.

Named as defendants in the suit are the US Anti-Doping Agency, USA Track and Field, the US Olympic Committee and the International Association of Athletics Federations.

USATF spokeswoman Jill Geer said the federation had to review the suit before commenting.

Another potential roadblock is jurisdiction. CAS secretary general Matthieu Reeb said on Friday the only legal option he knew of for Gatlin was to go before the Swiss Federal Tribunal, an appeal provided by Swiss law because CAS is based in Switzerland.

"We view this as an anti-doping matter and believe the appropriate forum for adjudication and resolution is through the American Arbitration Association or the International Court of Arbitration for Sport," USOC spokesman Darryl Seibel said.

The contention that Gatlin's first doping ban violated the ADA was raised by a member of the US arbitration panel that reduced his ban from eight years to four in January. Christopher L. Campbell, in a dissenting opinion, called it "blatant discrimination."

The suit alleges the defendants never provided Gatlin with information that Adderall, the drug he was prescribed, or any other ADD medications "could pose drug testing issues for a USATF event."

While competing for the University of Tennessee, Gatlin would stop taking Adderall a few days before a meet and never had a positive test. He followed the same routine before competing at the 2001 junior nationals, according to the lawsuit, but tested positive there for amphetamines.

Gatlin was suspended from international competition for two years, but the sport's governing body reinstated him after one year. Still, the IAAF warned Gatlin then that the 2001 incident counted as a doping violation and another would mean a lifetime ban.