In 1998 Jerman was vice-junior world champion in Super-G. He contested his first race in the Alpine Ski World Cup in the 1998/99 season . In addition to a few appearances in slalom and a race in giant slalom , he mainly competes in the Downhill and Super-G disciplines in the World Cup, as well as in the combination , in which he was able to classify himself in the top 10 for the first time in Wengen 2002. The combination was initially the only discipline in which he was able to regularly get World Cup points.
Since the 2006/07 season Jerman has been driving very well in the downhill. In December 2006 he was twelfth in Beaver Creek , ninth in Val Gardena and fourth or ninth in the runs in Bormio . On February 23, 2007 he then won the downhill in Garmisch-Partenkirchen . It was the first downhill victory of a Slovenian in the World Cup. A day later, he finished second behind Erik Guay . On December 29, 2009, he won his second World Cup victory on the downhill from Bormio. As a result, he was only able to place himself in the top ten in a few cases. Due to an injury, he had to pause almost the entire 2011/12 season.
From 2002 to 2011 Jerman took part in all Olympic Winter Games and World Championships . His best Olympic result was a 19th place in the combined in Turin 2006 . At the 2009 World Championships in Val-d'Isère , he achieved his best results with 12th place in the super combined and 13th place in the downhill.
On January 26, 2013, Jerman fell on the Streif in Kitzbühel and collapsed a little later. After first aid, he was flown to the hospital by helicopter, where he was diagnosed with a concussion. Three days after this accident, he announced his immediate resignation.