Immonen and two other former national skiers appeared in court Thursday to face charges of perjury in a doping trial that wrapped up last year.
The prosecution says that Immonen, Jari Isometsä and Harri Kirvesniemi committed perjury when they testified as witnesses. The men allegedly lied about their own use of prohibited substances and manipulation of haemoglobin levels during the trial. They also claimed to be unaware of doping in Finnish skiing.
While Immonen admitted to using the banned substance, Isometsä and Kirvesniemi maintained that they had not used EPO and that they had not misrepresented facts in 2011 during the trial.
The prosecution has called for suspended prison sentences for the offence.
Perjury in court is punishable by up to three years in prison.