Sprinter Dwain Chambers is due to find out whether he will be allowed to compete at next month's Olympic Games.
Mr Justice Mackay is expected to reveal whether or not he will grant an order to temporarily suspend a lifetime ban on Chambers competing at the Olympics.
The ban was imposed by the British Olympic Association (BOA) because of his self-confessed past use of performance-enhancing drugs.
The judge spent Thursday listening to the conflicting arguments over the athlete's attempt to win an injunction suspending the bylaw before a full trial of the issues in March next year.
Mr Justice Mackay commented to Jonathan Crystal, representing Chambers: "The reality is that you are saying 'put him on the plane'."
Mr Crystal, an expert in sports law, had told the judge that banning Chambers could deprive Britain of its best chance of winning a medal in the 100 metres in Beijing next month.
Chambers, 30, served a two-year suspension for using the designer steroid tetrahydrogestrinone (THG).
Mr Crystal said the BOA bylaw was unfair, contrary to competition law and an unreasonable restraint on trade.
"He represents our best chance of a podium finish in the 100 metres in Beijing," Mr Crystal said. "There would be no restriction to his selection for any other nation, save possibly Denmark and China."
He has already qualified to compete in the Olympic team after winning the 100 metres at the Olympic athletics trials in Birmingham last Saturday and setting his best time of the year of 10 seconds.
