Blake Leeper, a U.S. Paralympic sprinter born without legs below his knees, wants to run at the 2020 Tokyo Olympics against the fastest men in the world, but the next step in that quest will take place in a courtroom.

Leeper, a double amputee who competes with blade-like prosthetics, filed an appeal with the Court of Arbitration for Sport on Thursday to reverse a ruling by track and field’s international governing body that banned him from competing in major worldwide events. If his appeal is successful, Leeper would become the second track athlete using prosthetic legs to compete at an Olympics.

On Feb. 18, World Athletics, formerly known as the International Association of Athletics Federations (IAAF), declared Leeper ineligible, ruling that his blade-like prosthetics, similar to what South Africa’s Oscar Pistorius used at the 2012 London Olympics, give him an unfair advantage over able-bodied competitors.

Leeper, 30, has broken Pistorius’s Paralympian record in the 400 meters and cracked 44.3 seconds in the 400, a time fast enough to qualify for the U.S. Olympic trials, which will be held in June, if CAS rules in his favor. Leeper has been fighting since July to gain approval from World Athletics to compete in the world’s biggest events, and the body’s ruling this month provided another hurdle.

“The takeaway is that they’re showing evidence of they don’t want me there,” Leeper said Wednesday evening in a phone interview. “For me as an athlete, I train each and every day for a fair chance to compete at the highest level. That’s something I feel like I’m not receiving right now.”

Lawyers Jeffrey Kessler and David Feher, who also represented Pistorius during his legal fight to compete in London, have taken Leeper’s case pro bono. Based on the precedent set by Pistorius’s case, Kessler said he is confident CAS will rule in Leeper’s favor and in sufficient time to allow him to compete at the trials in Eugene, Ore.

“It is completely disheartening that after unanimously losing Pistorius, including by a decision in which their own selected arbitrator agreed, that you’d have the international governing body of track once again just brazenly trying to keep a disabled athlete from competing,” Kessler said. “It is maddening. It is not really understandable except for how deep-seated this adversity in that body is against the disabled competing on the world stage at the highest level against able-bodied runners when they’re able to do so.”

In World Athletics’ rule book under a section regarding “Assistance not Allowed,” Rule 6.3.4 includes, “The use of any mechanical aid, unless the athlete can establish on the balance of probabilities that the use of an aid would not provide them with an overall competitive advantage over an athlete not using such aid.”

“Mr Leeper’s application, including all supporting evidence, was thoroughly considered by World Athletics’ Assistance Review Group (ARG)," a World Athletics spokeswoman said in a statement. "The ARG concluded that Mr Leeper had not established that his prostheses do not provide him with an overall competitive advantage. Under the current rule, the burden of proof lies with the athlete to show that prostheses do not provide them with an overall competitive advantage. The current rule was introduced in 2015.”

Leeper’s best times would make him a viable threat to contend for a spot on the U.S. team. He finished fifth in the 400 meters at the U.S. championships in July, which qualified him for the U.S. team at the world championships. Leeper has no doubts he would make the Olympics if given a chance.

“Without being too cocky or confident, 1,000 percent,” Leeper said. “I am 100 percent ready. … I’m there to go in as a competitor, as a threat.”

Leeper’s lawyers will make a twofold argument. First, they say World Athletics violated precedent when, in 2015, they made a rule change that required runners who use prosthetics to prove their blades do not provide an advantage over able-bodied athletes. Previously, including when Pistorius won his appeal to compete at the 2012 London Games, the sport’s governing body had to prove the athlete received an advantage.

Second, Leeper’s lawyers will claim that, though Leeper shouldn’t have to bear the burden of proof, he has done so anyway. In his original application to World Athletics, which was filed July 3, Leeper included a report by research scientist and University of Colorado professor Alena Grabowski that concluded his blades do not provide a competitive advantage. Grabowski later wrote to World Athletics that its findings critiquing her report “were not scientifically correct.”

Leeper faces the same criticism Pistorius confronted as he aimed to compete in London: that his blades provide an unfair advantage because they provide an unnatural spring. How does Leeper respond to those who say a man without legs is at an advantage in a sprint?

“First, I laugh. Then I say, ‘Oh, you’re serious,’ ” Leeper said. “I tell people that it’s ridiculous. All the disadvantages I have to go through being born without legs: There’s some days when my legs are infected and swollen and they’re bleeding. I have to ice them down some days just to walk. People see the end result, which is me running fast. But they don’t understand the process of a man being born without legs trying to run with the fastest runners in the world. I tell people, walk a mile in my shoes? If you walked a mile in my legs …”

At the U.S. championships in July, Leeper won a semifinal 400 heat, crossing the line at Drake University in Des Moines to raucous cheers. He failed to make the U.S. team for the world championships as an individual in the next day’s final, but his fifth-place finish was good enough to qualify him as a possible choice for the 4x400 relay team.

But Leeper was competing in an unofficial capacity. His results were held in abeyance as World Athletics ruled on his eligibility; his times were all officially listed as “DQ.”

Some rivals believe the blades provide a competitive advantage, particularly along straightaways. American Michael Norman, one of the top 400 runners in the world, said this summer at the U.S. championships that blades give Leeper a disadvantage coming out of the blocks but give him a “killer kick” at the end of races. Those attributes, if he is ruled eligible and qualifies at the U.S. trials in June, could make him an appealing candidate as a relay member.

Leeper has faced personal challenges beyond competition. He tested positive for cocaine at the 2015 Paralympic U.S. championships and was banned from the sport for two years. He since has detailed his battle with and recovery from drug and alcohol addiction.

At the 2012 Paralympics, Leeper won silver in the 400, finishing behind only Pistorius, and bronze in the 200. Those 2012 Paralympics fueled Leeper’s desire to compete in the Olympics. He remembers lining up next to Pistorius in the 200-meter final and listening to how the stadium roared when Pistorius, who had just competed in the Olympics, was introduced.

“All disabled people had somebody to look up to, to give them hope, including myself,” Leeper said. “Being a part of that moment, even though it wasn’t really about me, really motivated me to show what you could possibly do as a disabled man. …

“The fact is, a lot of people might not even know my name or know my story. They’ll just see a disabled man born without legs running at the Olympic Games — for me, I see myself winning the Olympic Games. My message to the world, every child out there is, they told me I would never walk, and here I am running. If I’m being discriminated against at the highest level, imagine what the rest of the world is going through."