Former World No 1 Vijay Singh sued the PGA Tour on Wednesday, a week after golf's premier tour dropped a doping a case against the three-times major winner.
Singh was initially found by the PGA Tour to have breached the sport's doping rules after using a spray, which contains a banned substance, to treat an injury but was later cleared of any wrongdoing after winning an appeal.
He filed a lawsuit in the Supreme Court of the State of New York on Wednesday, and issued a statement saying the PGA Tour had damaged his reputation.
"I am proud of my achievement, my work ethic and the way I live my life," Singh said in the statement.
"The PGA Tour not only treated me unfairly, but displayed a lack of professionalism that should concern every professional golfer and fan of the game."
Although he never failed a drugs test, Singh was deemed to have breached golf's rules on doping when he told Sports Illustrated earlier this year he had used deer antler spray.
The spray was found to have contained small extracts of IGF-1, a growth hormone on the World Anti-Doping Agency's (WADA) list of prohibited substances.
The PGA Tour imposed a sanction on Singh following his admission but the Fijian appealed, saying he was unaware the spray contained any banned substances.
He was cleared last week when WADA informed the PGA Tour the use of deer antler spray was not prohibited unless a positive test resulted.
Singh's lawyers said on Wednesday the PGA Tour violated its duty of care by suspending the golfer without properly investigating the case.
"The PGA Tour could have known by conducting some basic testing and research, the product that Singh sprayed contained no active biological ingredient and could not possibly have provided any performance enhancement," Singh's attorney, Peter R. Ginsberg, said in a statement.
"The PGA Tour has now finally admitted that the use of deer antler spray is not prohibited.
"Rather than performing its duties to golfers first, and then determining whether there had been any violation of the Anti-Doping Program, the PGA Tour rushed to judgment and accused one of the world's hardest working and most dedicated golfers of violating the rules of the game."
The PGA did not immediately comment on the lawsuit.
Singh, 50, was ranked number one in the world on three separate occasions between 2004 and 2005. He also won three majors: the 2000 Masters and the 1998 and 2004 PGA Championship.